Lap times across years say as much about the weather as the class. % of STU is each class's best lap as a share of STU's on the same day, so the conditions drop out: 100% is level, less is quicker, and a move in it is the class getting faster or slower against the field.
Closest to the field:STU 100.0% of STU Eric Heinrich, Daytona International Speedway Runoffs 2015 race · T4 95.5% of STU John Heinricy, Virginia International Raceway Runoffs 2022 race
STUT4solid race · dashed qualifying · slower is lower
STUT4solid race · dashed qualifying · each class's best lap as a share of STU's at the same event (the reference class, changeable above); 100% is level, less is quicker, so up the chart is quicker
2:24.912Richard Astacio · fastest of 17 · top 5 within 2.6s+1.829s (+1.28%)
2:26.416Richard Astacio · fastest of 16 · top 5 within 1.5s+1.919s (+1.33%)
145.1Hugh Stewart+0.8 mph (+0.5%)
2:35.876Matt Spicuzzi · fastest of 12 · top 5 within 2.4s+2.920s (+1.91%)
2:35.757Matt Spicuzzi · fastest of 12 · top 5 within 2.7s+3.124s (+2.05%)
127.6Matt Spicuzzi-6.0 mph (-4.5%)
+9.341squal +10.964s
106.4%qual 107.6%
41 rule changes (STU: 15, T4: 26)9 cars added · 7 weight · 5 induction · 4 suspension & brakes · 4 tyres & wheels · 2 removed · 5 wording · 5 other · GT3U wheel and tyre options clarified: 15x7 with 225 section at +275 lbs; 15x9 with 245 section at +275 lbs plus 1.5%; 16–18x9 with 245 section at +275 lbs plus 3.0%. · STU cars at or under 2,825 lbs minimum weight limited to 8-inch wheels; over 2,825 lbs limited to 9-inch wheels. · STU GT3U minimum weight increases from GT3 race weight plus 225 to plus 275 pounds; 2.0L unrestricted engines add 75 lbs. · STU adds BMW M50B20TU engine, 1991 cc, minimum weight per chart, must meet all STU engine regulations. · STL, STU weight calculation procedure clarified: positive percentages added first, negative subtracted second, then fixed weights applied. · STU Honda K20C1 Turbo I4 turbo restrictor increases from 35mm to 36mm TIR. · STU GT86 Cup car must meet 2022 Toyota GR Cup rules, tires maximum 245 section width. · STU Mazda Renesis Street Port added to Table B with 2450 lbs minimum weight and 70mm throttle body options. · STU eliminates 33 and 34 mm inlet restrictor options, removing minimum weights of 2380 and 2525 lbs. · STU Mazda MZR engines may now use Fab 9 Elite NC MX5 Performance Intake manifold as alternative option. · T2-T4 adjustable toe links now allow performance alternative bushings and spherical bearings, previously only spherical bearings permitted. · STU Mazda MZR (LF, L3, L5) Turbo added; Goodwin intake removed, Jack Spania Racing 70 mm intake and Fab9 Tuning bottom-mount turbo kit approved. · T2, T3, T4 now allow under-dash electronics relocation for access after roll cage installation. · T4 Performance clarified: 1-piece alternative rotors permitted only at sizes listed in spec line; alternate brake kits may use matching 1-piece rotors. · STU 36mm restrictor revised to 2830 cc, 37mm to 2980 cc. · STU removes 275 tire option and 2% weight adder for cars over 3150 lbs; maximum section width now 245. · STU Honda K20 and K24 engines lose 2% weight penalty; minimum weight now per chart only. · STU Honda K24 engine swap weight increases by 2 percent, effective November 1, 2025. · T3 and T4 Mazda MX-5 Miata add permitted gearset kit PT#0000-02-6100 to Notes. · T4 MX-5 Miata 19-24 and 16-18, T3 MX-5 16-18 and Global Cup ND1/ND: discontinued DG Motorsports hardtop part #0000-07-5901 removed from permitted list.showhide
STU Wheel and tire requirements for GT3U #40679wordingwordingGT3U wheel and tyre options clarified: 15x7 with 225 section at +275 lbs; 15x9 with 245 section at +275 lbs plus 1.5%; 16–18x9 with 245 section at +275 lbs plus 3.0%.
T4 02-06 R53 Mini Cooper Hotchkins Rear Camber Arms #40677suspension & brakes
STU 9” Wheels #40433tyres & wheelsslowertyres & wheelsSTU cars at or under 2,825 lbs minimum weight limited to 8-inch wheels; over 2,825 lbs limited to 9-inch wheels.
STU Weight adjustment to former GT3U cars #40474weightslowerweightSTU GT3U minimum weight increases from GT3 race weight plus 225 to plus 275 pounds; 2.0L unrestricted engines add 75 lbs.
STU Request to allow BMW M50B20TU engine in STU #40202cars addedaddedSTU adds BMW M50B20TU engine, 1991 cc, minimum weight per chart, must meet all STU engine regulations.
STU Calculating Weight #40224wordingwordingSTL, STU weight calculation procedure clarified: positive percentages added first, negative subtracted second, then fixed weights applied.
STU Turbo Restrictor Size Increase Request #40008inductionfasterinductionSTU Honda K20C1 Turbo I4 turbo restrictor increases from 35mm to 36mm TIR.
STU GT86 Cups Car in STU #40028wordingwordingSTU GT86 Cup car must meet 2022 Toyota GR Cup rules, tires maximum 245 section width.
T4 2003 Honda Civic Si Classification #39999cars added
STU Mazda Rx-8 Renesis - Streetported Variant & Added Weight #39785cars addedaddedSTU Mazda Renesis Street Port added to Table B with 2450 lbs minimum weight and 70mm throttle body options.
STU Eliminate 33 and 34 mm TIRs #39872inductionremovedinductionSTU eliminates 33 and 34 mm inlet restrictor options, removing minimum weights of 2380 and 2525 lbs.
STU Fab 9 Racing Intake Manifold in STU #39767cars addedaddedSTU Mazda MZR engines may now use Fab 9 Elite NC MX5 Performance Intake manifold as alternative option.
T4 ND MX-5 Spec Line Rewrite Request #39802weight -100 lbs
T4 Allow Alt Bushing Material in Toe Links #39607suspension & brakesaddedsuspension & brakesT2-T4 adjustable toe links now allow performance alternative bushings and spherical bearings, previously only spherical bearings permitted.
STU Request for Permission on Aftermarket Turbo Kit and Intake #39529cars addedaddedSTU Mazda MZR (LF, L3, L5) Turbo added; Goodwin intake removed, Jack Spania Racing 70 mm intake and Fab9 Tuning bottom-mount turbo kit approved.
T4 Alternate Placement of Fuse Panel and Electronics Request #39370otheraddedT2, T3, T4 now allow under-dash electronics relocation for access after roll cage installation.
T4 Clarify T4 Brake Rotor Allowance #39503wordingwordingT4 Performance clarified: 1-piece alternative rotors permitted only at sizes listed in spec line; alternate brake kits may use matching 1-piece rotors.
STU Turbo Inlet Restrictor Table #38961wordingwordingSTU 36mm restrictor revised to 2830 cc, 37mm to 2980 cc.
STU 275 Tire Rule #38983tyres & wheelsslowertyres & wheelsSTU removes 275 tire option and 2% weight adder for cars over 3150 lbs; maximum section width now 245.
STU STU Honda Engine weight penalty #39375weightfasterweightSTU Honda K20 and K24 engines lose 2% weight penalty; minimum weight now per chart only.
T4 ND Spec Lines Wrong PT#'s #39170removedremovedT4 MX-5 Miata 19-24 and 16-18, T3 MX-5 16-18 and Global Cup ND1/ND: discontinued DG Motorsports hardtop part #0000-07-5901 removed from permitted list.
2:23.083Peter Cunningham · fastest of 16 · top 5 within 2.6s-3.144s (-2.15%)
2:24.497Chip Herr · fastest of 15 · top 5 within 3.8s-1.327s (-0.91%)
144.3Chip Herr-1.0 mph (-0.7%)
2:32.956Matt Spicuzzi · fastest of 10 · top 5 within 3.8s-1.474s (-0.95%)
2:32.633Alex Lozano · fastest of 10 · top 5 within 4.3s-1.575s (-1.02%)
133.7Alex Lozano+4.4 mph (+3.4%)
+8.136squal +9.873s
105.6%qual 106.9%
47 rule changes (STU: 18, T4: 29)12 weight · 9 cars added · 7 tyres & wheels · 3 engine · 1 aero · 1 induction · 1 removed · 6 wording · 7 other · STU Lotus Elise SC and Exige SC weight reduced from 2450 to 2250 lbs. · STU-TCR gains GT3 TCR spec lines; 275 tyre option now costs 150 lb adder, up from 100 lb. · Lotus Evora GT4 minimum weight drops to 2700 lbs; Elise Cup R to 2250 lbs; Elise SC and Exige SC to 2450–2550 lbs. · T2, T3, T4 spec table header changed from T2 to ET. · STU 2.8–3.2L N/A engines now permit 245 max tyre width; over 3150 lbs cars may run 275 with 2% weight penalty. · STU Mazda MZR intake manifold now allows Goodwin 61-2510 or Gato Performance 31972. · STU Honda JDM H23a added, 2259 cc, minimum weight per chart, must meet ST engine regulations. · STU wheels capped at 18 inches diameter; under 2,850 lbs max 8 inches wide, over 2,850 lbs max 9 inches wide. · STU-GT3U minimum weight reduced from plus 250 to plus 225 pounds; wheel and tyre options clarified with weight adjustments. · STU BMW N54/N55 3.0 classified at chart plus 3% minimum weight; N54 twin turbo not allowed. · STU Mini Cooper S SC pulley diameter reduced to 2.185 inches. · STU Honda K20C1 Turbo I4 exempted from 3% direct injection weight adder. · STU GT3U minimum weight increases 150 pounds to 250 pounds. · Ford SCCA Club Spec Mustang added to T3 at 3350 lbs; Mazda SCCA Club Spec MX-5 added to T4 at 2500 lbs. · STU Audi 1.8T Wagon removed; Porsche 944 1800cc weight to Chart, turbo inlet restrictor deleted. · STU-GT3 reclassified as STU-GT3U, effective 1 January 2026. · STU GT3 TCR may run 275-wide DOT tires with 100 lb weight penalty; A compound prohibited at 275. · T2, T3, T4: nine, nine, and thirty-seven expired spec lines removed effective 2025-01-01. · STL STU Mazda Miata alternate front hubs Mazda Motorsports Development Part #0000-04-5HUB-S1 approved. · STU BMW N54/N55 turbo inlet restrictors now required per GCR definition; twin turbo conversion to single turbo clarified. · T2, T3 Mustang spec lines remove redundant driveshaft allowance notes across six model year ranges. · T2, T3, T4 fuel cell installations may omit charcoal canisters, emissions valves, and sensors. · T2, T3, T4 brake specifications clarified: 2-piece rotors allowed in T2 within 5% OE diameter, T3 within 2% OEM diameter. · T2, T3, T4 fuel cell installations may remove charcoal canisters, emissions valves, and sensors. · Porsche Spec Boxster moves to T4, minimum weight 2750 lbs, ineligible for Runoffs until 3 Super Tour events. · T4 BMW 320i Spec Line: Turner Motorsports intercooler #024703TMS02 now allowed. · 2005 Cadillac CTS 3.6L 6-speed manual classified in T3 Spec. · STU Mini Cooper S SC: 1900 stock pulley spec to 2.565 diameter; 2100 now permits 2.285 diameter pulley.showhide
STU Lotus Weight Reduction E&O #38919weightfasterweightSTU Lotus Elise SC and Exige SC weight reduced from 2450 to 2250 lbs.
STU STU-TCR Adjustments #38723weightslowerweightSTU-TCR gains GT3 TCR spec lines; 275 tyre option now costs 150 lb adder, up from 100 lb.
STU Lotus Weight Reduction #38772weight -50 lbsfasterweightLotus Evora GT4 minimum weight drops to 2700 lbs; Elise Cup R to 2250 lbs; Elise SC and Exige SC to 2450–2550 lbs.
T4 Incorrect Touring Heading #38451wordingwordingT2, T3, T4 spec table header changed from T2 to ET.
STU 2.8-3.2L N/A Engine Allowances #38007tyres & wheelsfastertyres & wheelsSTU 2.8–3.2L N/A engines now permit 245 max tyre width; over 3150 lbs cars may run 275 with 2% weight penalty.
STU 2006-2015 Mazda Miata Intake Manifold #38422engineaddedengineSTU Mazda MZR intake manifold now allows Goodwin 61-2510 or Gato Performance 31972.
STU Requesting Approval of the JDM Honda h23a #38489cars addedaddedSTU Honda JDM H23a added, 2259 cc, minimum weight per chart, must meet ST engine regulations.
STU Wheel Size Inconsistency #38018tyres & wheelstyres & wheelsSTU wheels capped at 18 inches diameter; under 2,850 lbs max 8 inches wide, over 2,850 lbs max 9 inches wide.
STU Table C: STU-GT3U Clarification #38268weightfasterweightSTU-GT3U minimum weight reduced from plus 250 to plus 225 pounds; wheel and tyre options clarified with weight adjustments.
T4 Correct Ring and Pinion Ratio to T3, Sorry I Mean T4 3.7 V6 Stang #38041wording
STU BMW N54/N55 Engine Allowance Follow Up #37447cars addedaddedSTU BMW N54/N55 3.0 classified at chart plus 3% minimum weight; N54 twin turbo not allowed.
STU STU Mini Cooper pulley size clarification re: letter #36980 #37717inductionfasterinductionSTU Mini Cooper S SC pulley diameter reduced to 2.185 inches.
STU Question About a Weight Modifier #37782weightfasterweightSTU Honda K20C1 Turbo I4 exempted from 3% direct injection weight adder.
STU Increase Minimum Weight #37919weight +100 lbsslowerweightSTU GT3U minimum weight increases 150 pounds to 250 pounds.
T4 Request to Classify Club Spec in Appropriate Touring Classes #37523cars addedaddedFord SCCA Club Spec Mustang added to T3 at 3350 lbs; Mazda SCCA Club Spec MX-5 added to T4 at 2500 lbs.
STU Audi 1.8t Wagon STU Table B #36685cars addedremovedcars addedSTU Audi 1.8T Wagon removed; Porsche 944 1800cc weight to Chart, turbo inlet restrictor deleted.
STU Merger GT3 to STU #37486wordingunclearSTU-GT3 reclassified as STU-GT3U, effective 1 January 2026.
STU GT3 TCR Tire allowance #37494tyres & wheelsaddedtyres & wheelsSTU GT3 TCR may run 275-wide DOT tires with 100 lb weight penalty; A compound prohibited at 275.
T4 Remove spec lines that have expired #37269removedremovedT2, T3, T4: nine, nine, and thirty-seven expired spec lines removed effective 2025-01-01.
STU Request to Remove Miata Hubs from General category #37138cars addedaddedSTL STU Mazda Miata alternate front hubs Mazda Motorsports Development Part #0000-04-5HUB-S1 approved.
STU BMW N54/N55 Engine Allowance #37146wordingwordingSTU BMW N54/N55 turbo inlet restrictors now required per GCR definition; twin turbo conversion to single turbo clarified.
T4 Redundant Verbiage Regarding Mustang Spec Lines for Driveshaft #36484wordingwordingT2, T3 Mustang spec lines remove redundant driveshaft allowance notes across six model year ranges.
T4 R53 Mini Cooper S Weight Reduction Request #36612weight
T4 Move Spec Boxster to T4 #37158cars addedaddedPorsche Spec Boxster moves to T4, minimum weight 2750 lbs, ineligible for Runoffs until 3 Super Tour events.
STU R53 15% Pulley Request #36980enginefasterengineSTU Mini Cooper S SC: 1900 stock pulley spec to 2.565 diameter; 2100 now permits 2.285 diameter pulley.
2:26.227Thomas Noble · fastest of 18 · top 5 within 2.3s-1.656s (-1.12%)
2:25.824Thomas Noble · fastest of 17 · top 5 within 2.4s-2.586s (-1.74%)
145.3Thomas Noble+1.1 mph (+0.8%)
2:34.430Matt Spicuzzi · fastest of 15 · top 5 within 1.8s-2.973s (-1.89%)
2:34.208Alex Lozano · fastest of 14 · top 5 within 2.2s-3.673s (-2.33%)
129.3Alex Lozano-0.9 mph (-0.7%)
+8.384squal +8.203s
105.7%qual 105.6%
32 rule changes (STU: 4, T4: 28)8 weight · 5 cars added · 5 suspension & brakes · 4 aero · 2 induction · 1 engine · 1 removed · 2 wording · 4 other · STU RWD turbo cars no longer required to reduce inlet restrictor by 1 mm from table minimum. · T2 Mustang GT 5.0L 15-17 and 2018- now permit Track/Performance Package parts; T3 V6 15-17 clarified to allow Track/Performance package. · T2-T4 Ford Mustangs: remove 25 lb penalty for non-OEM driveshaft, clarify alternate driveshaft allowance. · Audi S4 (2000–2002) classified in T3 with 2671cc, 3400 lbs minimum weight, 38mm restrictor, allowing 800lb springs and intercooler. · T3 and T4 Mazda RX-8 may remove or disable factory oil injection system. · T2, T3, T4 driveshafts may use carbon fiber, aluminum, or steel; two-piece replaced with one-piece; non-OEM adds 25 lbs. · STU Mini Cooper S SC gains alternate LEAP OMICRON hood scoop part LEP-OMICRON3 as permitted option. · STU BMW S54 B32 OEM dry sump oiling system now permitted. · T2, T3, T4 Spec Lines remove wheelbase requirement, add Required Restrictor specification. · T2 and T3 Nissan 370Z front brake rotors increase to 355×32 mm, rears to 350×20 mm. · STL and STU now permit electric power steering pumps, OEM electric-assisted steering, or column-mounted electric steering assist systems. · T2, T3, T4 battery replacement no longer allows alternate manufacturer batteries within 10% OEM weight. · T4 now allows C-Spec touring cars to compete, in addition to existing B-Spec eligibility. · T2, T3, T4 spec lines expire 12/31/24; submit to appeal or cars are removed from class. · T3 Nissan 370Z now includes model years 2009–2022 with Nismo editions.showhide
STU RWD Turbo Disadvantage #36255inductionfasterinductionSTU RWD turbo cars no longer required to reduce inlet restrictor by 1 mm from table minimum.
T4 B8/8.5 Audi S4 T3 and T2 #36195cars addedaddedAudi S4 (2000–2002) classified in T3 with 2671cc, 3400 lbs minimum weight, 38mm restrictor, allowing 800lb springs and intercooler.
T4 Allow OEM Front Spoiler 06-08 Miata in T4 #35941aero
T4 R53 Mini Cooper S spec line request In #36056suspension & brakes
T4 Allow T4 and T3 RX8 to Disable/Remove Factory Oil Inj. #35761engineaddedengineT3 and T4 Mazda RX-8 may remove or disable factory oil injection system.
T4 2023 ND2 Miata Classification and Allowances #35837weight
T4 Errors and Omissions for 06-09 VW Rabbit Rotor #35851suspension & brakes
T4 Driveshafts #35916weightslowerweightT2, T3, T4 driveshafts may use carbon fiber, aluminum, or steel; two-piece replaced with one-piece; non-OEM adds 25 lbs.
T4 GCR ERROR - letter not properly applied to GCR #35999weight
T4 Allow any 400lb rear spring in the RX8 #35433suspension & brakes
T4 370Z Brake Rotor Size Correction #35487suspension & brakessuspension & brakesT2 and T3 Nissan 370Z front brake rotors increase to 355×32 mm, rears to 350×20 mm.
STU ST Electric-Assisted Steering Systems #35066aeroaddedaeroSTL and STU now permit electric power steering pumps, OEM electric-assisted steering, or column-mounted electric steering assist systems.
T4 More Car Lightening Stuff #35319wordingremovedT2, T3, T4 battery replacement no longer allows alternate manufacturer batteries within 10% OEM weight.
T4 Inclusion of B-C spec cars in T4 #35374cars addedaddedT4 now allows C-Spec touring cars to compete, in addition to existing B-Spec eligibility.
T4 T2-T4 Set expiration dates on spec lines #35378wordingremovedT2, T3, T4 spec lines expire 12/31/24; submit to appeal or cars are removed from class.
T4 Mazda MX-5 ND1 Spec Line Request #34232weight +50 lbs
T4 BRZ/FRS/86 Spring Allowance #35038suspension & brakes
2:00.389Johan Schwartz · fastest of 13 · top 5 within 2.3s-0.226s (-0.19%)
2:02.302Mark Liller · fastest of 14 · top 5 within 1.6s-30.055s (-19.73%)
144.0Mark Liller+0.1 mph (+0.1%)
2:10.514Devin Anderson · fastest of 24 · top 5 within 0.5s+0.937s (+0.72%)
2:11.962Devin Anderson · fastest of 23 · top 5 within 0.1s-13.481s (-9.27%)
127.8Raymond Blethen+0.5 mph (+0.4%)
+9.660squal +10.125s
107.9%qual 108.4%
23 rule changes (STU: 3, T4: 20)6 weight · 4 cars added · 4 suspension & brakes · 1 aero · 1 engine · 1 induction · 3 wording · 3 other · Mazda RX-8 T3 and T4 transmission and final drive pairing requirement removed; T4 gains Mazdaspeed radiator, spring kit, restrictor, spoiler, air dam. · T3 BMW 320i 14–15 gains aftermarket intercooler; T4 BMW 320i 14–15 loses it. · T3 and T2 Pontiac Solstice GXP 07-09 minimum ride height set to 3 inches. · STU adds 2022 Toyota GR Cup and GR86 Cup, both 2387cc, 2700 lbs, 18-inch wheels, 245/620R18 slicks. · STU Mazda BP5A now classified at 1839 cc displacement, 2510 lbs minimum weight, alternate intake manifold permitted. · STU minimum weights adjusted: 2450 cc to 2595 lbs, 2600 cc to 2710 lbs. · T2 and T3 Mustang 11-14 may remove upper grille fog lights, replace with mesh or screen. · T5 touring class added; T2-T5 cars may race one class up; T5 maximum tyre width 225 with minimum aspect ratio 45. · T2-T5 Touring front and rear suspension maximum negative camber clarified to 3.5 degrees.showhide
T4 Inclusion of similar car. (CLK 320) #34626other
T4 Rules Clarification for Mazda RX8 Spec Line #34395wordingwordingMazda RX-8 T3 and T4 transmission and final drive pairing requirement removed; T4 gains Mazdaspeed radiator, spring kit, restrictor, spoiler, air dam.
T4 rule book corrections #34437otheraddedT3 BMW 320i 14–15 gains aftermarket intercooler; T4 BMW 320i 14–15 loses it.
T4 Ride Height Correction for the T3 Solstice. #34615suspension & brakessuspension & brakesT3 and T2 Pontiac Solstice GXP 07-09 minimum ride height set to 3 inches.
STU 2022 Toyota GR Cup for STU #34449cars addedaddedSTU adds 2022 Toyota GR Cup and GR86 Cup, both 2387cc, 2700 lbs, 18-inch wheels, 245/620R18 slicks.
T4 2002-2006 Mini Cooper S R53 Spec Line Request #34336weight -50 lbs
T4 Mustang OEM Grill Request #33333aeroaddedaeroT2 and T3 Mustang 11-14 may remove upper grille fog lights, replace with mesh or screen.
T4 Mazda OEM LSD was letter 32655 typo #33666wording
T4 Allowable Springs and Sway Bars for 06-11 Civic si Spec Line #33294suspension & brakes
T4 Touring (T2-T5) Category #33617cars addedaddedT5 touring class added; T2-T5 cars may race one class up; T5 maximum tyre width 225 with minimum aspect ratio 45.
T4 ENO 9.1.9.2.D.1.e.1.a. #33651wordingwordingT2-T5 Touring front and rear suspension maximum negative camber clarified to 3.5 degrees.
2:00.615Johan Schwartz · fastest of 21 · top 5 within 2.6s+0.667s (+0.56%)
2:32.357Mark Liller · fastest of 19 · top 5 within 4.3s+31.874s (+26.46%)
143.9Johan Schwartz+0.1 mph (+0.1%)
2:09.577John Heinricy · fastest of 18 · top 5 within 0.7s-1.680s (-1.28%)
2:25.443John Heinricy · fastest of 18 · top 5 within 2.5s+14.484s (+11.06%)
127.4Nick Leverone-1.5 mph (-1.2%)
-6.914squal +8.962s
95.5%qual 107.4%
50 rule changes (STU: 21, T4: 29)10 weight · 7 tyres & wheels · 6 engine · 5 suspension & brakes · 4 cars added · 3 aero · 1 induction · 1 removed · 8 wording · 5 other · STU Mazda 13B Turbo added as Chart Limited displacement, streetport only, alternative turbos only. · STU OEM louver vents no longer count against vent allowance or 200 square inch limit. · STU non-4-valve engines gain 9% base engine weight reduction allowance; 2400cc minimum weight drops 1 lb to 2595. · STU normally-aspirated engines 2976cc–3200cc with single throttle body lose 10% base engine weight reduction allowance. · ST removes redundant language about engine balance shaft removal and alternate pulley installation. · STU cars that qualified for 9 inch wheels in 2021 may continue running them through 2022 only. · STU splitter definition clarified: must attach to lowest point of front, have no vertical deviations. · T2-T4 Touring cars with alternative springs now permitted to use performance top hats with spherical bearings on shocks and struts. · STU BMW E36 M3 (95-99) S52B32 minimum weight cut to 3110 lbs from 3200, displacement to 3152 cc. · STU BMW S50B32 Euro maximum displacement 3201 cc, minimum weight 3300 lbs, permits 0.040 overbore and 0.5 compression increase. · ST engine swap origin rule narrowed: North America changed to United States only for case-by-case approval. · STU Honda CRX 84-91 and Civic Del Sol 93-97 both ineligible for front-wheel-drive weight reductions. · STU wheel width rule clarified: under 2950 lbs uses max 8.0 inches, 2950 lbs and over uses max 9.0 inches. · STU single-throttle body cars get lower minimum weights: 2450cc to 2596 lbs, 2500cc to 2635 lbs, 2550cc to 2675 lbs. · T2-T4 touring cars model year 2018+ may use aftermarket ECU with 75 lb weight penalty via spec line adjustment. · STU single throttle body weight reduction removed; minimum weights revised down to 2990 lbs at 3000cc from 3300 lbs. · STU Audi A4 1.8T minimum weight fixed to 3050 lbs, K04 turbo removed, VF30 with 35mm restrictor required; Porsche 944 1800 weight fixed to 3050 lbs, VW/Audi 1.8L engine removed, 35mm inlet restrictor required. · STL and STU Improved Touring vehicles must now conform to section 9.1.4 Tires & Wheels. · T2-T4 grill opening removal for cooling permitted without 16 square inch limit; mesh shape must match factory. · STU engines may delete balance shafts and plug openings; alternate pulleys or gears allowed only for timing belt or chain operation. · STU hood vents now allow louvers within 200 square inches. · STU adds Honda K23 with 2354 cc displacement and chart minimum weight, K24 block allowed with K23 internals and head. · STU Honda K23 relaxes internal engine requirement, now needs only K23 crankshaft. · STL/STU intake manifold and cylinder head porting clarified as free; intake and exhaust porting wording removed. · T2, T3, T4 clarify grill opening removal limited to 16 square inches for radiator cooling; mesh shape must be retained. · T2, T3, T4 radiator and coolant hoses may be replaced with aftermarket options; coolant temp sensor modification permitted. · T2, T3, T4: clarified that 'permitted' or 'allowed' parts in spec lines are alternatives to category rule allowances, not replacements. · T4 adds 2014 VW Jetta 1.8T TSI to Spec Lines.showhide
STU Request Mazda 13 B turbo #32668cars addedaddedSTU Mazda 13B Turbo added as Chart Limited displacement, streetport only, alternative turbos only.
STU Hood Vents and Intercooler Scoops #32733aeroaddedaeroSTU OEM louver vents no longer count against vent allowance or 200 square inch limit.
STU Non 4 valve weight reduction removed #32808weightfasterweightSTU non-4-valve engines gain 9% base engine weight reduction allowance; 2400cc minimum weight drops 1 lb to 2595.
STU Error in new minimum weight table when combined with other text #32711engineslowerengineSTU normally-aspirated engines 2976cc–3200cc with single throttle body lose 10% base engine weight reduction allowance.
STU Redundant Language in May GCR #32713wordingwordingST removes redundant language about engine balance shaft removal and alternate pulley installation.
T4 Request Wider Wheels for Hyundai Tiburon #32536tyres & wheels
STU Opposed to the Proposed STU Weight Chart #32381tyres & wheelsaddedtyres & wheelsSTU cars that qualified for 9 inch wheels in 2021 may continue running them through 2022 only.
STU Clarification request for GCR 9.1.4.D.3.a Splitter Definition #32414wordingwordingSTU splitter definition clarified: must attach to lowest point of front, have no vertical deviations.
T4 Request to Add Spec Line for 2004-2009 Mazda3 i 2.0 #32395weight
T4 Request Alternate Front & Rear Strut/Shock Top Hats #32452suspension & brakesaddedsuspension & brakesT2-T4 Touring cars with alternative springs now permitted to use performance top hats with spherical bearings on shocks and struts.
STU Request Adjustment to Min Weight for STU BMW E36 M3 (95-99) #31535weight -90 lbsfasterweightSTU BMW E36 M3 (95-99) S52B32 minimum weight cut to 3110 lbs from 3200, displacement to 3152 cc.
STU BMW E36 M3 Canadian (North American) S50B32 engine #31866engineaddedengineSTU BMW S50B32 Euro maximum displacement 3201 cc, minimum weight 3300 lbs, permits 0.040 overbore and 0.5 compression increase.
STU Engine Swap Origin Country #32209wordingwordingST engine swap origin rule narrowed: North America changed to United States only for case-by-case approval.
STU CRX/Civic Del Sol #32214weightslowerweightSTU Honda CRX 84-91 and Civic Del Sol 93-97 both ineligible for front-wheel-drive weight reductions.
STU Error correction #32383wordingwordingSTU wheel width rule clarified: under 2950 lbs uses max 8.0 inches, 2950 lbs and over uses max 9.0 inches.
STU Single TB Weight Modifiers Add to Chart #32393weightfasterweightSTU single-throttle body cars get lower minimum weights: 2450cc to 2596 lbs, 2500cc to 2635 lbs, 2550cc to 2675 lbs.
T4 Request to Allow the Use of Aftermarket ECU's in Touring #31067engineaddedengineT2-T4 touring cars model year 2018+ may use aftermarket ECU with 75 lb weight penalty via spec line adjustment.
T4 Request JWT BSR Kit for 02-06 Nissan Sentra SE-R/Spec V #31685other
T4 Please Confirm Touring 4 (98-00) BMW 323 is E46 generation #31972other
T4 RX-8 Spring Part Numbers (E&O) #32151suspension & brakes
STU Single TB Weight Modifiers #31449weightfasterweightSTU single throttle body weight reduction removed; minimum weights revised down to 2990 lbs at 3000cc from 3300 lbs.
STU Request to Remove A4 1.8t from STU Spec Line Tables #31465weightslowerweightSTU Audi A4 1.8T minimum weight fixed to 3050 lbs, K04 turbo removed, VF30 with 35mm restrictor required; Porsche 944 1800 weight fixed to 3050 lbs, VW/Audi 1.8L engine removed, 35mm inlet restrictor required.
STU Improved Touring Tires #32063tyres & wheelstyres & wheelsSTL and STU Improved Touring vehicles must now conform to section 9.1.4 Tires & Wheels.
T4 Reply to letter #31486/29879 T2-T4 Grill openings #31935aerofasteraeroT2-T4 grill opening removal for cooling permitted without 16 square inch limit; mesh shape must match factory.
STU Request Allowance for Balance Shaft Delete in STU #31434enginefasterengineSTU engines may delete balance shafts and plug openings; alternate pulleys or gears allowed only for timing belt or chain operation.
STU Request Louvers in hood vents #31916aeroaddedaeroSTU hood vents now allow louvers within 200 square inches.
T4 Request Allowances for 2005 - 2010 Mustang #31624wording
STU Request to Add Honda K23 Spec Line #30682cars addedaddedSTU adds Honda K23 with 2354 cc displacement and chart minimum weight, K24 block allowed with K23 internals and head.
STU RE: Aug FT letter 30682 #31060enginefasterengineSTU Honda K23 relaxes internal engine requirement, now needs only K23 crankshaft.
STU Throttling Device Clarification #31323wordingwordingSTL/STU intake manifold and cylinder head porting clarified as free; intake and exhaust porting wording removed.
T4 Reply to letter 29879 T2-T4 Grill Openings #31486wordingwordingT2, T3, T4 clarify grill opening removal limited to 16 square inches for radiator cooling; mesh shape must be retained.
T4 Please Adjust 98-00 BMW 323 Min Weight to Reflect Current Class #31595weight -200 lbs
T4 Consolidate 12-13 and 14-15 Honda Civic Si spec lines for T4 #31596removed
T4 Request to clarify radiator hoses #31682otheraddedT2, T3, T4 radiator and coolant hoses may be replaced with aftermarket options; coolant temp sensor modification permitted.
T4 Clarify Permitted/Allowed #31743wordingwordingT2, T3, T4: clarified that 'permitted' or 'allowed' parts in spec lines are alternatives to category rule allowances, not replacements.
1:47.078Joe Moser · fastest of 30 · top 5 within 2.0s-1.843s (-1.69%)
1:47.441Joe Moser · fastest of 28 · top 5 within 1.8s-1.946s (-1.78%)
146.9Kip VanSteenburg
1:54.397Stephen Blethen · fastest of 47 · top 5 within 0.9s-2.169s (-1.86%)
1:55.929John Heinricy · fastest of 46 · top 5 within 1.0s-0.994s (-0.85%)
127.3Alexander Schefer
+8.488squal +7.319s
107.9%qual 106.8%
32 rule changes (STU: 12, T4: 20)6 cars added · 5 weight · 3 tyres & wheels · 2 induction · 2 suspension & brakes · 1 aero · 1 engine · 9 wording · 3 other · STU fender flare wording clarified: flare of exterior contour may not change wheel opening size, location or shape from side view. · STU Mazda 12A Bridgeport weight reduced from 2550 lbs to 2350 lbs. · T3 Honda Civic Type-R 2020+ allowed brake rotor #45251-TGH-A01 with 25 lb penalty. · STU fender flare rules clarified: maximum 2 inches total, must cover tire contact patch from above, cannot alter body configuration or wheel opening geometry. · STU Honda S2000 now allows F20/F22 K24 crankshaft with chart weight for achieved displacement. · ST oil coolers and filters now explicitly listed as addable or substitutable parts in vents and breathers section. · T2-T4 clutch discs and pressure plates must be at least 95% of factory OEM weight, bolted to unmodified stock flywheel. · ST 90-05 Mazda Miata allowed alternate front wheel hub Mazda Motorsports Development Part #0000-04-5HUB-S1. · ST cars may now relocate ABS actuation hardware and wiring anywhere in the engine compartment. · STU Porsche PDK automatic transmission limited to 8 forward speeds; sequential DCT systems require 3.5% minimum weight increase. · STU Mazda 13B Street Port 2400 removes choke location rule, allows auto-type 2bbl with any dual-Y manifold. · STU driveshaft and half-shafts now explicitly permitted in steel or aluminum, removing OEM material requirement. · Toyota Supra 2020- added to T2 with 2998 cc engine, 3450 lbs minimum weight, 19×10 wheels, 295 tyres. · STU Mazda 13B Spec and Bridge Port removed; Street Port added at 2400 lbs minimum weight. · T2 BMW M2 CS Cup 2020+ classified at 2979 cc, 3625 lbs, 295 tires, 10.5×18 wheels, 380/390 mm brakes. · T4 Ford Mustang V6 05-10 allows GT 8.8 rear axle with 3.55 final drive, plus 25 lb penalty. · T3 Scion FR-S/Toyota 86 and Subaru BRZ capped to 2021 model year; T4 models capped to 2021. · ST aero devices and reference areas must include end plates, exclude fasteners under 1/2" protrusion. · T3 Alfa Romeo 4C Launch Edition variant now allowed.showhide
STU STU Fender flares #30696wordingwordingSTU fender flare wording clarified: flare of exterior contour may not change wheel opening size, location or shape from side view.
STU Request weight reduction for 12A bridgeport motor in Miata #30751weight -200 lbsfasterweightSTU Mazda 12A Bridgeport weight reduced from 2550 lbs to 2350 lbs.
T4 Wrong Part Number on 320i Spec Line #30645wording
T4 Civic Type R Brake Rotors #29817weightslowerweightT3 Honda Civic Type-R 2020+ allowed brake rotor #45251-TGH-A01 with 25 lb penalty.
STU Request for Fender Flare Clarification #30375wordingwordingSTU fender flare rules clarified: maximum 2 inches total, must cover tire contact patch from above, cannot alter body configuration or wheel opening geometry.
STU Provision for Interchangeable Engine Components Already Allowed #30342engineaddedengineSTU Honda S2000 now allows F20/F22 K24 crankshaft with chart weight for achieved displacement.
STU ST Oil Coolers E&O Correction to 9.1.4.2.H #30388wordingwordingST oil coolers and filters now explicitly listed as addable or substitutable parts in vents and breathers section.
T4 Request consistency review in GCR #30263wordingwordingT2-T4 clutch discs and pressure plates must be at least 95% of factory OEM weight, bolted to unmodified stock flywheel.
STU Super Touring Alternate Miata Hubs #30345cars addedaddedST 90-05 Mazda Miata allowed alternate front wheel hub Mazda Motorsports Development Part #0000-04-5HUB-S1.
STU Brake Component Relocation #29990suspension & brakessuspension & brakesST cars may now relocate ABS actuation hardware and wiring anywhere in the engine compartment.
STU Porsche PDK #30081wordingwordingSTU Porsche PDK automatic transmission limited to 8 forward speeds; sequential DCT systems require 3.5% minimum weight increase.
STU Reference Letter #29333 Proposed STU 13B Spec Line Changes #30086wordingwordingSTU Mazda 13B Street Port 2400 removes choke location rule, allows auto-type 2bbl with any dual-Y manifold.
STU Drive Shaft Request #30087otherotherSTU driveshaft and half-shafts now explicitly permitted in steel or aluminum, removing OEM material requirement.
T4 2021 Toyota Supra #29567cars addedaddedToyota Supra 2020- added to T2 with 2998 cc engine, 3450 lbs minimum weight, 19×10 wheels, 295 tyres.
T4 Change part numbers on BRZ, FRS lines in T4 #30104wording
T4 T4 Mustang Axle Ratio and Wheels #30149tyres & wheels
STU 13B Rules Adjustment #29333cars addedremovedcars addedSTU Mazda 13B Spec and Bridge Port removed; Street Port added at 2400 lbs minimum weight.
T4 Request to Classify BMW M2 CS #29523cars addedaddedT2 BMW M2 CS Cup 2020+ classified at 2979 cc, 3625 lbs, 295 tires, 10.5×18 wheels, 380/390 mm brakes.
T4 Allow the SpecMX-5 Update Kit Into Touring 4 for the MX-5 #29681other
T4 Request Mustang 8.8†rear axle replacement #29860cars addedaddedT4 Ford Mustang V6 05-10 allows GT 8.8 rear axle with 3.55 final drive, plus 25 lb penalty.
T4 Cap year range on all 86s #29908wordingwordingT3 Scion FR-S/Toyota 86 and Subaru BRZ capped to 2021 model year; T4 models capped to 2021.
STU Request clarification on wing measurement #29640aeroaeroST aero devices and reference areas must include end plates, exclude fasteners under 1/2" protrusion.
2:27.883David Fiorelli · fastest of 14 · top 5 within 4.1s
2:28.410Anthony Geraci · fastest of 14 · top 5 within 3.1s
144.2David Fiorelli
2:37.403John Heinricy · fastest of 20 · top 5 within 2.5s
2:37.881Chi Ho · fastest of 19 · top 5 within 1.6s
130.2Chi Ho
+9.471squal +9.520s
106.4%qual 106.4%
42 rule changes (STU: 17, T4: 25)9 cars added · 5 engine · 5 weight · 4 suspension & brakes · 2 tyres & wheels · 1 aero · 11 wording · 5 other · STU fender flare rule reworded: now per-corner up to 2" total, 1% weight penalty applies to entire modification. · STL and STU clarify weight adjustment calculation order: engine adjustments first, then chassis percentage additions, subtractions, and fixed pounds. · STL STU rear wing Gurney flap terminology clarified from wicker to Gurney flap in mounting and chord rules. · STU request for alternate intake manifold denied; no change to rules. · GT3 and STU add Borg-Warner EFR6258 turbocharger to approved turbo lists. · STU large displacement turbo engines limited by GCR turbo list; no BoP change granted. · STU sequential shifters referred to Board of Directors for approval; no rule change effective. · Request to add vehicle to T2, T3, T4 roster; refer to letter #27663 in June 2020 Fastrack for decision. · STU Mazda 13B Bridge Port and Street Port added with 2550 lbs and 2250 lbs minimum weight respectively. · 2004 Mercedes Benz CLK 320 Coupe classified in T4 at 3200 lbs with 3299cc engine, 17-inch wheels, 245 tyres, EIBACH PN# 2563.140 springs allowed. · T3 BMW Z3 M & Coupe 98-99 minimum weight reduced to 3150 lbs. · STU Honda S2000 gains HKS Supercharger kits 12001-AH006 and 12001-AH010 as allowed options. · STU Lotus Elise Cup R and SC Exige SC gain 100 lbs minimum weight to 2300, 2500. · STU Volkswagen GTI/GLI MK5 and Jetta Mk4 may now install turbo inlet restrictor in OEM housing, per TIR spec. · STU Honda K20C1 Turbo I4 restrictor reduces from 36mm to 35mm. · STU GM Ecotech LNF now permitted without turbo, with LE5 head and intake manifold, meeting STL specs. · STU Porsche 944 now permits VW/Audi 1.8L and 2.0L turbo engines as alternates to original. · STU vehicles over 2951 lbs base weight may use 9 inch wide wheels, changed from 2950 lbs. · STU turbocharged engines now use base weight instead of minimum weight; DFI cars add 3% to base weight. · Pontiac Solstice GXP and Saturn Sky move from T2 to T3; wheels widen to 18x9.5, Sky weight drops to 3200 lbs. · Mazda RX-8 Base/R3/Sport/GT (04-12) classified in T3 effective 2020-02-01. · T2 must have fire system installed; T3 and T4 may have one per GCR 9.3. · T3 Ford Mustang EcoBoost gains three transmission gear ratio options. · T3 and T4 Mazda RX-8 Base/R3 (04-12) reclassified to include Sport and GT variants. · Toyota 86 GT variant (2017–) added to T3 and T4 spec lines. · STU allows OEM electronic throttle bodies, manual conversion, cam changes, and manual-to-electronic conversion with same inner diameter.showhide
STU Request for Advanced Aero Rule Wording Clarification. #29124wordingwordingSTU fender flare rule reworded: now per-corner up to 2" total, 1% weight penalty applies to entire modification.
STU Minimum Weight Determination #27695wordingwordingSTL and STU clarify weight adjustment calculation order: engine adjustments first, then chassis percentage additions, subtractions, and fixed pounds.
STU ST Gurney flap Wicker clarification #29012wordingwordingSTL STU rear wing Gurney flap terminology clarified from wicker to Gurney flap in mounting and chord rules.
T4 Scion FRS Solo Spec Coupe Gear Ratio #29021other
STU Request for Alternate Intake Manifold #26514wordingunclearSTU request for alternate intake manifold denied; no change to rules.
STU Request for Addition to GT3 Approved Turbo List #27576cars addedaddedGT3 and STU add Borg-Warner EFR6258 turbocharger to approved turbo lists.
STU Request BoP for my Car #29004wordingunclearSTU large displacement turbo engines limited by GCR turbo list; no BoP change granted.
STU Sequential Shifters in STU #29031wordingunclearSTU sequential shifters referred to Board of Directors for approval; no rule change effective.
T4 Request to Add a Vehicle to the Roster (contd.) #27698wordingunclearRequest to add vehicle to T2, T3, T4 roster; refer to letter #27663 in June 2020 Fastrack for decision.
STU Rotary Help #27833cars addedaddedSTU Mazda 13B Bridge Port and Street Port added with 2550 lbs and 2250 lbs minimum weight respectively.
T4 Request to Classify 2004 Mercedes Benz 320 CLK #27663cars addedadded2004 Mercedes Benz CLK 320 Coupe classified in T4 at 3200 lbs with 3299cc engine, 17-inch wheels, 245 tyres, EIBACH PN# 2563.140 springs allowed.
T4 Request to change allowed header part # for T4 06-15 Miata #28223wording
T4 Z3M Roadster Weight #28437weightfasterweightT3 BMW Z3 M & Coupe 98-99 minimum weight reduced to 3150 lbs.
STU Request to approve Honda S2000 HKS supercharger #27281otheraddedSTU Honda S2000 gains HKS Supercharger kits 12001-AH006 and 12001-AH010 as allowed options.
STU Request BoP on the Lotus #27637weight +100 lbsslowerweightSTU Lotus Elise Cup R and SC Exige SC gain 100 lbs minimum weight to 2300, 2500.
STU Turbo Inlet Restrictor On MK5 Volkswagen #27704otherslowerSTU Volkswagen GTI/GLI MK5 and Jetta Mk4 may now install turbo inlet restrictor in OEM housing, per TIR spec.
STU Honda K20C1 removal #27732engineslowerengineSTU Honda K20C1 Turbo I4 restrictor reduces from 36mm to 35mm.
STU Change GM LNF 2.0 Allowance to LSJ Engine for Viable STL 2.0 #27884engineaddedengineSTU GM Ecotech LNF now permitted without turbo, with LE5 head and intake manifold, meeting STL specs.
STU Alternate Engine for Porsche 944 #28259engineaddedengineSTU Porsche 944 now permits VW/Audi 1.8L and 2.0L turbo engines as alternates to original.
STU Please Modify the STU Wheel Size Rule for Clarity #27694weightfasterweightSTU vehicles over 2951 lbs base weight may use 9 inch wide wheels, changed from 2950 lbs.
STU Turbo Engine Cars Base Weight #28032wordingwordingSTU turbocharged engines now use base weight instead of minimum weight; DFI cars add 3% to base weight.
T4 Request for 12-13 and 14-15 Honda Civic Springs #27848suspension & brakes
T4 Request to Clarify T4 05-10 Mustang Spring Allowance #27899suspension & brakes
T4 Request to Allow Brake Upgrade on T4 Mustang #27329suspension & brakes
T4 Please Switch the Solstice GXP as Specified in T2, to T3 #27413cars added -50 lbsfastercars addedPontiac Solstice GXP and Saturn Sky move from T2 to T3; wheels widen to 18x9.5, Sky weight drops to 3200 lbs.
T4 Request to Classify all Mazda RX8 Models in T3/T4 #27606cars addedaddedMazda RX-8 Base/R3/Sport/GT (04-12) classified in T3 effective 2020-02-01.
T4 T4 RX8 Classification Error #27902cars addedaddedT3 and T4 Mazda RX-8 Base/R3 (04-12) reclassified to include Sport and GT variants.
T4 Request to add Toyota 86 GT to Spec Line #27910cars addedaddedToyota 86 GT variant (2017–) added to T3 and T4 spec lines.
STU Request for an electronic throttle body #27342engineaddedengineSTU allows OEM electronic throttle bodies, manual conversion, cam changes, and manual-to-electronic conversion with same inner diameter.
1:59.948Kevin Boehm · fastest of 25 · top 5 within 3.5s
2:00.483Kevin Boehm · fastest of 25 · top 5 within 2.5s
143.8Kevin Boehm
2:11.257John Heinricy · fastest of 25 · top 5 within 0.2s
2:10.959Nick Leverone · fastest of 25 · top 5 within 0.6s
128.9Tommy Boileau
+10.476squal +11.309s
108.7%qual 109.4%
37 rule changes (STU: 22, T4: 15)8 cars added · 6 engine · 4 induction · 3 aero · 3 suspension & brakes · 1 weight · 11 wording · 1 other · STU wing assembly wording corrected: no part may be higher than roof height. · T2, T3, T4 spare tire and cover removal wording clarified; removable covers now explicitly allowable to remove. · STU Nissan SR20DET removes -2mm penalty from Table B. · STU allows alternate intake manifolds on case-by-case basis; stock throttle device and manifold otherwise required. · STU aftermarket side skirts now allowed if they meet 3-inch ride height, lack ducts except jacks or exhaust, don't exceed fascia width, stay below door bottom, and don't reinforce chassis. · STU wheel flare wording clarified: each fender may be flared to 2" with 1% weight penalty, maintaining OEM profile. · STL and STU ride height measurement clarified: lowest rocker panel point without driver, excluding pinch weld. · STU Mazda 13B Bridge Port now permits ELITE ROTARY SHOP FD V2.0 intake manifold; stock throttle body requirement removed. · STU Mazda MZR gains alternate Goodwin intake manifold option with stock or Acura throttle body. · STU alternate suspension components rule moved from section E to section D. · STU Honda/Acura B20 now permits B16 or B18 VTEC cylinder head and matching intake manifold. · STU flared fenders up to 2" with 1% weight penalty moved from base to Advanced Aero. · STU Honda Civic Si TCA 2017- requires 37mm TIR throttle as of June 1, 2019. · STU BMW S54B32 OEM classified separately from E46, displacement 3246 cc, minimum weight 3300 lbs, OEM engine mandatory. · Honda Civic Si 2017- added to STU with 1500cc displacement, 2800 lbs minimum weight, OEM engine and bodywork, specific HPD parts allowed. · STU BMW E46 S54 OEM 3246cc added at 3300 lbs minimum; no Super Touring allowances, OEM intake and cams, 1mm overbore, compression +0.5 permitted. · STU Mazda 13B and 13B Bridge Port may use 13B RE or REW housings and intake with turbo removed. · STU Honda K24 may use intake part numbers 17100-RRB-A00 or 17100-PRB-A10. · STU Mazda 12A Bridge Port added, minimum weight 2550 lbs, Nikki or Auto-type carburettor with specified modifications. · STU World Challenge car weight rule deleted; no replacement specified. · STU AWD/RWD cars no longer must reduce restrictor 1 mm from table. · STU rear wing maximum 12" cord, 72 sq in end plates each, roof height max, body width limit. · T4 and T3 Mazda MX-5 hardtop rules clarified: any OEM or aftermarket top permitted if retaining OEM silhouette; specific part numbers listed. · T2, T3, T4 now allow any thermostat serving original equipment intent only. · T3 and T4 Mazda MX-5 Miata eligibility capped at 2016–2018 model years. · STU adds Honda K20C1 Turbo I4, 1996 cc, 3025 lbs minimum weight, 36mm TIR required. · T4 Celica GT wheelbase 2600 and 15x7 wheels added; Forte years narrowed; Fiesta ST starts 2014; Fiat 124 years 16-18 added; battery rule clarified. · T1–T4 spec car classifications clarified with permitted parts, rule conformance versions, and exclusions of other touring modifications. · T2–T4 subframe bushings now permitted to be replaced with non-spherical bushings of any material.showhide
STU Request to correct E&O advanced aerodynamics #27290wordingwordingSTU wing assembly wording corrected: no part may be higher than roof height.
T4 Request spare tire/wheel clarification #27012wordingfasterT2, T3, T4 spare tire and cover removal wording clarified; removable covers now explicitly allowable to remove.
STU Remove -2mm penalty from SR20DET Nissan #26982enginefasterengineSTU Nissan SR20DET removes -2mm penalty from Table B.
STU Request clarification for manifold and throttle in STU #27004wordingwordingSTU allows alternate intake manifolds on case-by-case basis; stock throttle device and manifold otherwise required.
STU Request to clarify afterrmarket side skirts exhaust exit #26814aeroaddedaeroSTU aftermarket side skirts now allowed if they meet 3-inch ride height, lack ducts except jacks or exhaust, don't exceed fascia width, stay below door bottom, and don't reinforce chassis.
STU Wheel Flare wording #26872wordingwordingSTU wheel flare wording clarified: each fender may be flared to 2" with 1% weight penalty, maintaining OEM profile.
T4 Request to allow piggy back ECU on 2000 Mazda Protégé #26085engine
T4 Request helper spring as optional #26678suspension & brakes
STU Request Ride Height Clarification #26597wordingwordingSTL and STU ride height measurement clarified: lowest rocker panel point without driver, excluding pinch weld.
STU Request to Use Japanese Mazda 13b Intake Manifold #25790engineaddedengineSTU Mazda 13B Bridge Port now permits ELITE ROTARY SHOP FD V2.0 intake manifold; stock throttle body requirement removed.
STU Request Alternate Intake for Mazda MZR In a Rear Wheel Drive App. #26352inductionaddedinductionSTU Mazda MZR gains alternate Goodwin intake manifold option with stock or Acura throttle body.
STU E&O Suspension #26424wordingwordingSTU alternate suspension components rule moved from section E to section D.
STU Revisit B20 VTEC #26530engineaddedengineSTU Honda/Acura B20 now permits B16 or B18 VTEC cylinder head and matching intake manifold.
STU Move Flared Fenders to STU Advanced Aero #26564aeroaeroSTU flared fenders up to 2" with 1% weight penalty moved from base to Advanced Aero.
STU TCA Civic SI E&O #26606inductionslowerinductionSTU Honda Civic Si TCA 2017- requires 37mm TIR throttle as of June 1, 2019.
STU S54 Spec line #26620cars addedcars addedSTU BMW S54B32 OEM classified separately from E46, displacement 3246 cc, minimum weight 3300 lbs, OEM engine mandatory.
T4 Request to classify 2000 - 2001 BMW 323 #25096cars added
STU Request to Class Assignment for 2017 Civic #24287cars addedaddedHonda Civic Si 2017- added to STU with 1500cc displacement, 2800 lbs minimum weight, OEM engine and bodywork, specific HPD parts allowed.
STU Request to run E46 3246cc in STU #25126cars addedaddedSTU BMW E46 S54 OEM 3246cc added at 3300 lbs minimum; no Super Touring allowances, OEM intake and cams, 1mm overbore, compression +0.5 permitted.
STU Engine Classification for Rotary #25564engineaddedengineSTU Mazda 13B and 13B Bridge Port may use 13B RE or REW housings and intake with turbo removed.
STU K24/K20 Head Swap Clarification/Amendment #25899otheraddedSTU Honda K24 may use intake part numbers 17100-RRB-A00 or 17100-PRB-A10.
STU Request to Classify 12a Bridge Ported Rotary Engine #25985cars addedaddedSTU Mazda 12A Bridge Port added, minimum weight 2550 lbs, Nikki or Auto-type carburettor with specified modifications.
STU World Challenge Car Eligibility #26387wordingunclearSTU World Challenge car weight rule deleted; no replacement specified.
STU Request a phone call for discussion regarding weight #26398inductionfasterinductionSTU AWD/RWD cars no longer must reduce restrictor 1 mm from table.
STU Advanced Aero E&O #26413aeroaddedaeroSTU rear wing maximum 12" cord, 72 sq in end plates each, roof height max, body width limit.
T4 Correct Mazda MX-5 Hard Top Notes #26137wordingwordingT4 and T3 Mazda MX-5 hardtop rules clarified: any OEM or aftermarket top permitted if retaining OEM silhouette; specific part numbers listed.
T4 Consider opening class rules to allow any thermostat #26187engineaddedengineT2, T3, T4 now allow any thermostat serving original equipment intent only.
T4 Cap 2016 Mazda Miata year at 2018 #26388cars addedremovedcars addedT3 and T4 Mazda MX-5 Miata eligibility capped at 2016–2018 model years.
T4 2012-2015 Honda Civic Si Performance Request #26129suspension & brakes
STU Request to Equalize Direct Injected Turbo Cars #24890cars addedaddedSTU adds Honda K20C1 Turbo I4, 1996 cc, 3025 lbs minimum weight, 36mm TIR required.
T4 Errors, Omissions, and Updates (Various) #22414wordingwordingT4 Celica GT wheelbase 2600 and 15x7 wheels added; Forte years narrowed; Fiesta ST starts 2014; Fiat 124 years 16-18 added; battery rule clarified.
T4 Request for Adjustments to fiat 124 specline #25371induction
T4 Add Clarification to Spec Car Classifications Vehicle Spec #25774wordingwordingT1–T4 spec car classifications clarified with permitted parts, rule conformance versions, and exclusions of other touring modifications.
T4 Clarify Subframe Bushings Permitted for T2-T4 #25800suspension & brakesaddedsuspension & brakesT2–T4 subframe bushings now permitted to be replaced with non-spherical bushings of any material.
T4 Consider Solo SSC cross over classification into T4 #25802cars added
Every event the class ran, at any track, oldest to newest on the chart and newest first in the table. Each point is the class's best lap as a share of STU's best on the same day: the weather and the day cancel out, so one figure compares across years where lap times cannot; a class that suits one track more than another still reads differently there. It still moves when the yardstick's own balance changes or its field thins, and an event the yardstick did not run has no point. A best from fewer than three cars is greyed. The rule changes that took effect between two events are folded between their rows.