These are the vehicle preparation rules for the Tuner Category of SCCA National Time Trials Competition. As with Sport Category, they are broken down into an Overview and then the "Authorized Modifications" (i.e., what you can do to your car and have it stay in Tuner Category).

1. Overview

1. Philosophy

The Tuner Category is meant for street-driven cars with bolt-on modifications that offer a degree of adjustability. Vehicle modifications are meant to fit between the current Sport and Max Categories, providing a natural competition outlet for auto enthusiasts using sports cars and sedans equipped with common suspension and engine modifications compatible with street use.

Modifications must still be bolt-on modifications; in most cases bolting to the OE locations, but different from Sport Category these parts may be more "tunable." Items like adjustable ride-height coilovers, more complex sway bars and, for some cars, ECU hardware changes are allowed. Suspension geometry-altering items like bump-steer correction or roll-center correction kits will not be allowed. As this is a street car, aftermarket aero items such as wings, splitters, spoilers and diffusers will not be allowed.

Tuner Category is a restricted ruleset. If a modification is not specifically authorized in these Rules, it is not allowed. (If it doesn’t say you can, you can’t.)

2. Safety

1. Vehicles running in Sport, Tuner, Prepped and Max Categories must meet Safety Level 1 Standards.

A. Roll bars, cages, racing harnesses and other safety equipment may be added, and must meet manufacturers' guidelines for installation. It is highly recommended that they at least meet the minimum for Safety Level 2 or Safety Level 3 Standards.

B. Nothing in the rules prevents you from adding safety equipment; the minimum amount of modification to install safety equipment is allowed.

C. To facilitate safety, vehicles that have an added roll bar may remove carpet, seats and trim (including convertible tops) behind the front seats. Vehicles that have an added roll cage may remove carpet, seats and trim (including convertible tops) other than the dash.

2. Fuel cells may be used in cars with the following restrictions and allowances:

A. OE lines may be replaced in conjunction with a fuel cell provided they are shielded.

B. Any fuel lines—including gauge and vent lines—that pass into or through the driver/passenger compartment, shall be of steel tube or metal braided hoses or bulkheaded.

C. Drivers of cars with modified or replaced OE fuel lines or tanks must wear a suit, shoes, gloves and underwear as specified in SCCA Time Trials Safety Level 2 Standards.

D. Vehicles with modified or replaced OE fuel lines or tanks must have an on-board fire suppression (fire bottle or system) meeting SCCA Time Trials Safety Level 2 Standards.

E. Participants are cautioned that this is not an allowance to maximize fuel delivery by installing higher-performance parts than authorized by category rules. (E.g., installing an upgraded fuel pump if it's not otherwise allowed.)

3. Vehicle Eligibility

1. To be eligible for Sport Category:

A. A minimum of 1,000 of that model must have been produced that model year for road use.

B. The vehicle must be capable of being licensed for normal road use in North America and delivered through the manufacturer's North American retail sales outlets.

4. General Modification Rules

The following items are guidelines for general repair and modifications in Sport and Tuner Categories:

A. Other than when necessary for safety enhancements, you may not perform an otherwise unlisted modification in order to facilitate a permitted one.

B. Any part which becomes partially or completely detached during on-track sessions must be fixed and inspected by officials before that vehicle can return to the track. If the part is an aerodynamic addition, the part shall be completely removed for the remainder of the competition.

C. Parts (other than brakes and fluids) are not permitted to be replaced or changed after the car has passed tech inspection unless an Event Official has determined the part to be unsafe or broken badly enough that not changing it would keep the participant from the event.

D. Expendable replacement parts (e.g., bearings, seals, gaskets, filters, belts, bolts, bulbs, batteries, clutch discs, pressure plates, suspension bushings, drivetrain mounts, fenders, trim pieces, fuel filler caps, electrical sensors, etc.) may be used provided they are essentially identical to the standard parts (e.g., have the same type, size, hardness, weight, material, specifications, etc.), are used in the same location, and provide no performance benefit. These allowances are strictly to allow components to be replaced from alternate sources other than the original manufacturer. They should not be construed as an allowance to replace components with those which could be considered a “higher performance” alternative.

E. Any repairs must comply with factory-authorized methods and procedures, or industry standard methods, as follows: If the OE does not provide an appropriate method of repair, industry standard methods and procedures may be used. Such repairs may not result in a part or combination of parts that provides a competitive advantage (e.g., significant change to weight, suspension control, power, etc.) as compared to the standard part(s). Competitors are strongly cautioned to use this allowance to make common-sense repairs only. It is not permitted to use non-compliant parts even if they have been set to OE specifications.

F. Except for authorized modifications, other modifications or equipment will place the car in higher levels as appropriate. Configurations involving damaged parts (e.g., blown fuses) are not typically authorized by the manufacturer and hence are not allowed.

G. Vehicles may be street-driven cars, and SCCA does not encourage or condone the breaking of laws governing pollution control systems or the alteration of street-driven vehicles contrary to state and Federal laws regarding their use. It continues to be the responsibility of the individual to comply with such state and federal laws.

2. Interior and Bodywork

1. Interior

1. A hole may be added through the bodywork to route a remote reservoir for shocks/struts and hose to a remote mounting location. Such holes may serve no other purpose.

2. Any steering wheel may be used. An alternate steering wheel assembly—including all mounting hardware—which replaces an airbag-equipped wheel is not required to have an airbag. An alternate wheel is not required to have a horn button.

3. Any shift linkage may be used.

2. Bodywork

1. Front hoods, engine covers, trunk lids and hatches not containing glass, front fenders, rear fenders not part of chassis structure (unibody), front and rear bodywork, and side skirts may be replaced with factory parts or exact duplicates in order to facilitate allowed modifications.

2. Factory rub strips may be removed.

3. OE “pop-up” headlights may be replaced with static headlights, provided the replacement units are intended for automobile use on public roads as a primary means of illumination, and retain high and low beams as originally provided by the manufacturer. Minor repositioning of the headlights can accommodate the alternate headlight, but the unit may not be relocated, and the repositioning may serve no other purpose. All associated hardware may be removed, replaced or modified.

4. Bolt-on tow hooks and tie downs may be modified or replaced. Addition of tow hooks and tie downs are permitted, and location is unrestricted. Non-standard tow hooks shall serve no other function.

5. Fenders may be rolled, but no material may be added or removed.

3. Wheels and Tires

1. Wheels

1. Any width or diameter wheel and wheel spacers may be used provided it complies with the following:

A. Non-metallic wheels must be certified/approved from an appropriate, recognized standards organization. (e.g., FIA, SFI, SAE, TUV, etc.)

B. Wheel spacers are permitted.

C. Wheel studs, lug nuts, valve stems (including pressure-relief types) and/or bolt length may be changed. Wheel bolts may be replaced with studs and nuts, but the number of fasteners may not be changed.

D. Tire pressure monitoring sensors may be removed.

E. Centerlock/spline drive/knock-off type hubs may be converted to lug-type hubs.

2. There are no wheel weight restrictions in Tuner Category.

2. Tires

1. Tires must meet the eligibility requirements of the Sport Category, but do not have to meet Sport Category width limits.

2. Tuner Tire Width Limits

Tires shall have a section width up to and including the following (mm):




Tuner 1 (T1)

2-Wheel Drive





Tuner 2 (T2)

2-Wheel Drive



All-Wheel Drive


Tuner 3 (T3)

2-Wheel Drive



All-Wheel Drive


Tuner 4 (T4)

2-Wheel Drive



All-Wheel Drive


Tuner 5 (T5)

2-Wheel Drive



All-Wheel Drive


3. Cars in Tuner Classes 2–5 and are otherwise legal for Tuner Category may bump up classes based on tire size. Cars in Tuner 1 with oversized tires will go into their appropriate Prepped or Max Category class.

4. Brakes

1. Brakes

1. Non-standard brake rotors may be used provided they are of equal or larger dimensions.

2. Aluminum rotor hats are allowed.

3. Cars originally equipped with solid (non-vented) rotors may utilize vented rotors.

4. Brake calipers and mounting brackets may be replaced provided they bolt to the standard locations and the number of pistons is equal to or greater than standard. A functioning emergency brake of the same type, operation, and actuation as OE must be present. Drum brakes may be replaced with disc brakes of a diameter equal to or greater than the inside diameter of the standard drum. Such conversions must be bolted, not welded, to the axle/trailing arm/upright and must include an integral, redundant emergency brake. Changes to backing plates/dust shields/brake lines to accommodate these changes are permitted but may serve no other purpose.

5. Air ducts may be fitted to the brakes and changes may be made made in the body/structure for their use. Ducts or holes may serve no other purpose. Backing plates and dirt shields may be modified or removed.

5. Steering and Suspension

1. Steering

Steering rack bushings may be replaced but must attach in the factory location(s) without additional modification or changes. Steering rack position may not be changed. The amount of metal in a replacement bushing may not be increased relative to the amount of metal found in a standard bushing for the particular application. Solid metal bushings are specifically prohibited. This does not allow shimming or otherwise relocating the steering rack.

2. Shocks and Struts

1. Shocks and Strut Replacement Allowances:

A. Any shock absorbers may be used.

B. Shock absorber mounting brackets which serve no other purpose may be altered, added, or replaced, provided that the attachment points on the body/frame/subframe/chassis/suspension member are not altered. This installation may incorporate an alternate upper spring perch/seat and/or mounting block (bearing mount). The system of attachment may be changed.

C. The number of shock absorbers shall be the same as standard.

D. No shock absorber may be capable of adjustment while the car is in motion, unless fitted as original equipment.

E. MacPherson strut equipped cars may substitute struts and/or may use any insert. This does not allow unauthorized changes in suspension geometry or changes in attachment points (e.g., affecting the position of the lower ball joint or spindle). It is intended to allow the strut length changes needed to accommodate permitted modifications which affect ride height and suspension travel.

2. The following additional allowances apply to cars originally equipped with separate spring and shock absorber assemblies.

A. Coil springs may be relocated so they encircle the body of the shock absorber in a “coilover” configuration.

B. Coil spring perches may be modified, added, or replaced and their position may be adjustable.

C. Additional bolt holes may be drilled for coilover assembly mounting brackets. This does not permit any modifications to the frame or unibody beyond the allowed mounting holes.

3. Springs

Springs must be of the same type as the original (e.g., coil, leaf, torsion bar, bellows) and except as noted herein, must use the original spring attachment points. This permits multiple springs, if they use the original mount locations. Coil spring perches originally attached to struts or shock absorber bodies may be changed or altered and their position may be adjustable. Spacers are allowed above or below the spring. Coil springs may incorporate spring rubbers. Suspension bump stops may be altered or removed.

4. Anti-Sway (Roll) Bars

Substitution or removal of sway bars (at one or both ends of the car) and supporting hardware (brackets, end links, bushings, etc.) is permitted. Tow hooks may be removed for the instillation of sway bars.

5. Strut Braces

Strut bars are permitted with all types of suspension, subject to the following constraints:

1. A 2-point strut bar may be added, removed, modified, or substituted, but only with another 2-point strut bar.

2. A triangulated (3-point) strut bar may be removed, modified, or substituted; substitution may be with either a triangulated or a 2-point strut bar. The connection to the chassis (e.g., firewall, bulkhead) must be in the standard location.

3. Lower suspension braces must be attached to the lower suspension pickup point locations on the chassis within 2 inches (50.8mm) in any direction of the actual suspension attachment to the chassis.

4. Except for standard parts, no connections to other components are permitted. Additional holes may be drilled for mounting bolts. Only “bolt-on” attachment is permitted. Interior trim panels may be modified to allow installation of strut bars. Holes or slots may be no larger than necessary and may serve no other purpose. This does not permit any modifications to the frame or unibody beyond the allowed mounting holes.

6. Suspension

1. Ride height may only be altered by suspension adjustments, the use of spacing blocks, leaf spring shackles, torsion bar levers, or change or modification of springs or coil spring perches. This does not allow the use of spacers that alter suspension geometry, such as those between the hub carrier and lower suspension arm.

2. Suspension bushings may be replaced with bushings of any materials (except metal) if they fit in the original location. Offset bushings may be used. In a replacement bushing, the amount of metal relative to the amount of non-metallic material may not be increased. This does not authorize a change in type of bushing (e.g., ball and socket replacing a cylindrical bushing) or use of a bushing with an angled hole whose direction differs from that of the original bushing. If the standard bushing accommodated multi-axis motion via compliance of the component material(s), the replacement bushing may not be changed to accommodate such motion via a change in bushing type, for example to a spherical bearing or similar component involving internal moving parts. Pins or keys may be used to prevent the rotation of alternate bushings but may serve no other purpose than that of retaining the bushing in the desired position.

3. The following allowances apply to strut-type suspensions. Adjustable camber plates may be installed at the top of the strut and the original upper mounting holes may be slotted. The drilling of holes to perform the installation is permitted. The center clearance hole may not be modified. Any type of bearing or bushing may be used in the adjustable camber plate attachment to the strut. The installation may incorporate an alternate upper spring perch/seat and/or mounting block (bearing mount). Any ride height change resulting from installation of camber plates is allowed. Caster changes resulting from the use of camber plates are permitted.

4. Camber bolts may be installed providing these parts use the original, unmodified mounting points and meet the restrictions specified in Sport Category. Caster changes resulting from the use of camber bolts are permitted.

5. Camber kits (also known as camber compensators) may be installed. These kits consist of either adjustable length arms or arm mounts (including ball joints) that provide a lateral adjustment to the effective length of a control arm. Alignment outside the factory specifications is allowed. The following restrictions apply:

A. On double/unequal arm (e.g., wishbone, multi-link) suspensions, only the upper arms OR lower arms may be adjustable, but not both. Non-integral longitudinal arms that primarily control fore/aft wheel movement (e.g., trailing arm(s) or link(s) of a multi-link suspension) may not be replaced, changed, or modified.

B. On arm-and-strut (MacPherson/Chapman) suspensions, the lower arms may be adjustable OR other methods of camber adjustment as allowed by the previous sections may be used, but NOT both.

C. The non-adjusting control arms for vehicles having integral bushing/arm assemblies may be replaced subject to the following restrictions.

a. Arm length must remain the same as OE.

b. The part may not be adjustable.

c. The replacement arms must attach to the original standard mounting points. All bushings must meet the requirements of this section. Intermediate mounting points (e.g., shock/spring mounts) may not be moved or relocated on the arm. The knuckle/bearing housing/spindle assembly cannot be modified or replaced.

d. Any allowed arm must be commonly available (or have been available) at SCCA supporting partner Tire Rack, for regular retail sales and without custom order. Parts do not have to be sourced from Tire Rack, but they must be as they would have come off the shelf there, or the part must be on a specific approval list.

e. If you believe there is a commonly available retail unit which otherwise fits the intent of these Rules but is not available at Tire Rack you may write in for specific approval of that brand and model.

6. On swing or trailing arm suspensions, the main arms may not be modified or replaced, but lateral locating links/arms may be modified or replaced.

7. Front wheel drive (FWD) cars with rear beam axles may use shims between the rear axle and hubs.

8. The replacement arms or mounts must attach to the original standard mounting points. All bushings must meet the requirements of Tuner Category Rules. Intermediate mounting points (e.g., shock/spring mounts) may not be moved or relocated on the arm, except as incidental to the camber adjustment. The knuckle/bearing housing/spindle assembly cannot be modified or replaced.

9. Changes in suspension geometry are not allowed except as incidental to the effective arm length change.

Note: Many modern suspension designs known by other names, actually function as double A–arm designs. These include the rear suspensions on 1988-on Honda Civic/Integra, Chrysler/Plymouth/Dodge Neon, BMW E36, and most “multi-link” and are covered by the double/unequal arm rule.

10. On strut-equipped cars, the strut’s lower integral mounting bracket, for attachment to the upright or spindle, is unrestricted provided it attaches to the standard location. Any resulting change to the position of the strut centerline is allowed. Such brackets shall serve no other purpose. This does not allow for changes to the integral steering arm on cars that have the steering arm integrated with the strut body.

11. Changes in alignment parameters that result directly from the use of the allowed components are permitted. For example, the dimensional changes resulting from the use of a cylindrical offset bushing that meets the restrictions of Tuner Category Rules are allowed, including those resulting from a change in the pivoting action to:

A. About the mounting bolt, or

B. About the bushing itself.

12. Subframe mount bushings may be replaced but must attach in the standard location(s) without additional modification or changes. Subframe position may not be changed. The amount of metal in a replacement bushing may not be increased relative to the amount of metal found in a standard bushing for the particular application. Solid metal bushings are specifically prohibited.

13. The following list is Solid Axle Rear Wheel Drive (RWD) Suspension Allowances:

A. Addition or replacement of suspension stabilizers (linkage connecting the axle housing or De Deion to the chassis, which controls lateral suspension location) is permitted.

B. Traction bars or torque arms may be added or replaced.

C. A Panhard rod may be added or replaced.

D. The upper arm(s) may be removed, replaced, or modified and the upper pickup points on the rear axle housing may be relocated.

E. The lower arms may be replaced or modified and the lower pickup points on the rear axle housing may be relocated.

F. Differential covers and attaching hardware may be replaced.

G. Methods of attachment and attachment points are unrestricted but may serve no other purpose (e.g., chassis stiffening). This does not authorize removal of a welded-on part of a subframe to accommodate the installation.

The following non-adjustable control arms not available at Tire Rack are allowed in SCCA Time Trials Tuner Category:

There are no models listed at this time.

7. Sub Frame Connectors

Longitudinal (fore-aft) subframe connectors (SFCs) are permitted with the following restrictions:

1. They must only connect previously unconnected boxed frame rails on unibody vehicles.

2. Each SFC must attach at no more than three (3) points on the unibody (e.g., front, rear, and one point in between such as a seat mount brace or rocker box brace).

3. SFCs must be bolted in place and not welded.

4. No cutting of OE subframes or floorpan stampings is permitted. Drilling is permitted for mounting bolts only.

5. No cross-car/lateral/triangulated connections directly between the driver’s side and passenger’s side SFCs are permitted. Connections to OE components such as tunnel braces or closure panels via bolts are allowed and count as the third point of attachment. No alteration to the OE components is permitted.

6. SFCs may not be used to attach other components (including but not limited to torque arm front mounts or driveshaft loops) and may serve no other purpose.

6. Electrical

1. Electrical

Except for those with electric and hybrid powertrains, Tuner Category vehicles may do everything allowed in Sport Category plus the list below.

1. OE traction control systems may be electrically disabled, but not removed or altered in any other way.

2. The make, model number and size of the battery may be changed, but not its voltage.

3. Relocation of the battery or batteries is permitted but not into the passenger compartment. If the battery is relocated and the original battery tray can be removed by simply unbolting it, the tray may be removed or relocated with the battery. Holes may be drilled for mounting or passage of cables. Longer or shorter cables may be substituted to permit relocation.

4. The number of battery or batteries may not be changed from standard. The area behind the rearmost seat is not considered to be within the passenger compartment. The area under the rearmost seat is within the passenger compartment.

5. Holes may be drilled in the firewall to permit passage of electrical wiring. It should be no larger than necessary to facilitate allowed modifications in this section and shall serve no other purpose.

6. Any starter, generator or alternator may be used in the original position. An alternator or generator must have an electrical output (including amperage) equal to or greater than the original equipment unit. Any generator or alternator pulley and belt of the same type as standard may be used.

7. Electrically driven fans are allowed. Flex fans are not allowed.

7. Engine and Drivetrain

1. Engine Control/ECU/Electronics

In addition to the Sport Category allowed modifications, the following modifications may be made to Tuner Category ECU/engine controls:

1. For all model years, the following allowances apply:

A. The standard PCM/ECU may be re-programmed without restriction.

B. Fuel pressure regulator(s) may be replaced in lieu of electronic hardware or software alterations. It is not permitted to mechanically alter the fuel pressure regulation AND make other hardware or software changes to engine operation.

C. Ignition timing may be set at any point on factory-adjustable distributor ignition systems.

D. Alternate computer control modules may be used whenever an equivalent change to the conventional system is allowed. For example, alternate computer module control of ignition settings or fuel injection is allowed.

2. 1995 and older vehicles, in addition, may replace the standard PCM/ECU without restriction.

3. Boost may be controlled through a mechanical boost controller.

2. Intake

As utilized only on engines originally equipped with forced induction, induction charge heat exchangers (also known as “intercoolers” or “charge air coolers” [CACs]) are unrestricted in size and configuration and are subject to the following restrictions: 

1. Air-to-air CACs and radiators for air-to-liquid CACs must be cooled only by the atmosphere except for standard parts.

2. Body panels, fascias, or structural members may not be cut or altered to facilitate CAC installation.

3. Cooling System

1. Engine cooling radiators may be replaced or added with alternate parts subject to the following restrictions:

A. Radiator core dimensions (width, height, thickness) cannot be smaller than the standard part.

B. Radiator must mount to OE radiator mounts.

C. Fluid capacity and dry weight of the radiator must be no less than that of the standard part. Installation of an alternate radiator may serve no other purpose (e.g., to allow a cold air intake passage).

D. The installation of water expansion tanks is allowed. A water expansion tank is the container which catches overflow coolant.

E. Thermostats may be added or substituted. A thermostat is a device which controls the passage of water.

F. Modifications necessary for additional radiators must be the minimum required for installation.

4. Engine Rebuilds/Service Limits

1. Engine Service Limits

A. Engines may be rebored to the manufacturer’s first standard overbore, not to exceed 0.020 inch (0.508 mm). Sleeving is allowed to repair to the standard bore. Only OE-type standard or first overbore pistons of the same configuration and of the same or greater weights are permitted. No interchange between cast and forged pistons is allowed.

B. Valve seats and guides in older engines originally designed for leaded fuel may be only substituted with alternate components if the dimensions are the same as those of the standard components.

5. Transmissions/Differentials/Transfer Cases

1. Limited Slip Differentials (LSD): Any mechanical LSD unit is permitted. Final drive ring and pinion gears may be replaced with alternate parts, provided the final drive does not change.

2. Any mechanical shift linkage may be used.

3. Any clutch disc and pressure plate of stock diameter and design may be used, provided that they can be bolted directly to an unmodified stock flywheel.

4. Alternate flywheels are permitted. Flywheel material shall be the same type as OE and the ring gear diameter must be the same as the OE flywheel.

5. Differential mount bushings may be replaced but must attach in the standard location(s) without additional modification or changes. Differential position may not be changed. The amount of metal in a replacement bushing may not be increased relative to the amount of metal found in a standard bushing for the particular application. Solid metal bushings are specifically prohibited.

6. Exhaust

1. Exhaust manifolds, headers, downpipes, and associated EGR tubes may be replaced with alternate units. Exhaust exit may be relocated provided it meets safety requirements. Relocation of the oxygen sensor on the header is permitted. Exhaust heat shields which cover only, and attach solely to, these parts may also be replaced, removed, or modified. All other exhaust heat shields may be modified the minimum amount necessary to accommodate allowed alternate exhaust components. Mounting brackets/hardware which serve no other purpose are considered part of the exhaust components.

2. Catalytic converters – Any catalytic converters are allowed, provided they meet the following restrictions.

A. Catalytic converters must attach within 18” (457.2 mm) of the original unit.

B. Multiple catalytic converters may be replaced by a single unit.

C. The inlet of the single replacement converter may be located no further downstream than 18” (457.2 mm) along the piping flow path from the original exit of the final OE converter.

D. The extents of an OE converter are defined by the expansion chamber in which the catalyst is contained, regardless of placement within larger exhaust sections.

E. Replacement converters must have a minimum catalyst density of 100 cells per inch and minimum substrate length of 3” (76.2 mm).

Note: The SCCA does not encourage or condone the breaking of laws governing pollution control systems or the alteration of street-driven vehicles contrary to state and Federal laws regarding their use. It continues to be the responsibility of the individual to comply with such state and federal laws.

7. Oil/Lubrication

Oil pans, oil pickups and differential covers may be modified or substituted. Addition or modification of windage trays or crankshaft scrapers is not allowed. Engine oil, transmission fluid, differential fluid and power steering fluid coolers may be added or substituted (including oil to coolant heat exchangers), but may not serve any additional purpose.

8. Engine Accessories

Any accessory pulleys and belts of the same type (e.g., V-belt, serpentine) as standard may be used. This allowance applies to accessory pulleys only (e.g., alternator, water pump, power steering pump and crankshaft drive pulleys). It does not allow replacement, modification, or substitution of pulleys, cogs, gears or belts which are part of cam, layshaft, or ignition drive or timing systems, etc. Any crankshaft damper or pulley may be used. SFI-rated dampers are recommended. Supercharged cars may not change the effective diameter of any pulley which drives the supercharger.

8. Other

1. Out of Production Cars

Where a car is out of production and the manufacturer is either out of business, stocks no parts or no longer has a required part, a part of any origin but as similar as possible to the original may be substituted.

1. The entrant must be prepared to show documentary evidence that one of the three circumstances above applies and that the substituted part is as similar as possible under the circumstances.

2. Substitute parts which provide improvements in performance (e.g., superior gearing, lighter weight, better camshaft profile, etc.) are not permitted under this allowance.

9. Fuel

1. Allowed Fuel

1. Sport and Tuner Category vehicles will use fuel which is “Federally approved for use on public highways.” This does not allow racing-type fuels which are available at service station pumps.

2. Fuels comprised of more than 15% ethanol may only be used when specified by the manufacturer (e.g., in the owner’s manual for flex-fuel vehicles).

3. Propane or Compressed Natural Gas (CNG) fuel may be used in any category provided that the following conditions are met:

A. The tank must be located in a safe location on the car and be firmly and securely mounted. This does not permit the cutting of vehicle sheet metal (e.g., the trunk floor) for tank installation.

B. The tank must conform to Federal and local container standards and have an emergency relief/cut-off control.

C. For use of propane or CNG as a fuel, no changes to the induction system of the engine may be made with the exception of the necessary fuel lines to the carburetor or fuel injection. There may also be no other engine parts changed.

D. The entire system must meet local ordinances covering the use and transmission of compressed gas.

E. Propane or CNG may not be used in combination with another fuel.

10. Classing

1. Tuner Category Exclusion List

Even more awesome cars we considered, and ultimately decided, "This is certainly a dream car, and Max Category is the place for dream cars, whether it's the car you dream to build, or the car you dream to buy."

Corvette Z06, ZR1 2015+
Corvette ZR1, 2006-2014
Viper GTS-R or ACR
720 S

2. Tuner Category - Alternate Motorsports Series Classing

This is where we're going to put cars that might not quite meet the rules, but we think they can go in this category anyway.

1. Cars listed as eligible in and prepared to the SCCA Road Race National Touring 2, 3 and 4 Rules are permitted to compete in their respective Time Trials Tuner Class provided they run on Time Trials legal tires. Vehicles with this allowance are not permitted to interchange preparation rules otherwise.

2. Cars listed as eligible in and prepared to the SCCA Road Race National Spec Miata Rules are permitted to compete in Time Trials Tuner Class 5 (T5) provided they run on Time Trials legal tires. Vehicles with this allowance are not permitted to interchange preparation rules otherwise.

Note: SCCA Solo Street Prepared has been rejected for Tuner Category inclusion because a full-tilt Street Prepared car is an engine-swapped, intake-manifold customized Frankenstein creation which is awesome, but doesn't belong in Tuner Category.

3. Tuner 1 (T1)

  R8 V10 2013-15
M3/M4 CS 2018+
ATS-V 2016-2019
CTS-V 2009-2015
Corvette Z06 2006-2014
Corvette (Naturally aspirated) 2015+
Camaro ZL1 (all)
Viper 2003-07
550 Maranello 1996-2001
Mustang GT500
GT-R, GT-R Nismo 2008+
911 Turbo, Turbo S 2013-2015
GT3 1999-2005
Cayman Base, S 2017+

4. Tuner 2 (T2)

  NSX 1990-2005
  R8 4.2 V8 2006-15
  RS3 2015+
  TT RS 2012+
  M3 2007-2013
  335i 2006-2013
  M235i 2014-2016
  135i 2008-2013
  M2 Competition 2018+
Corvette Z06 2001-2005
Corvette 1984 - 2014 Not Otherwise Classed or Excluded
Camaro SS, SS 1LE 2010+
Camaro Z/28 2014-2015
Crossfire SRT6
Viper 1991-02
Stealth R/T Turbo
Mustang GT, GT350 2015+
Mustang Boss 302 2012-2013
Exige S 2006-2008
  911 Turbo 1997-04
  911 S/4S 2012-2014
911 (SCCA T2)
Cayman R 2011-12

5. Tuner 3 (T3)

Integra Type R
TT S 2006-2014
S3 2013+
E30/E36/E46 M3
M5 1988-19995
Z3 M Roadster/Coupe 1996-2002
Z4 Roadster/Coupe 2005-08
335D 2006-2013
CTS-V 2004-2007
  SS 2014-2017
Camaro V6 2016+
Camaro 4T
Cobalt SS (FI) 2005-10
Neon SRT-4
Charger R/T 2001+
124 Abarth
Focus RS 2015+
Mustang GT 1994-2014
Mustang EcoBoost 2015+
Mustang V6 2011+
Civic Type R
Genesis R Spec (2.0T & 3.8)
G35 2002-2007
  RC200T F Sport 2015+
GS300 V8 1997-2005
Cooper S JCW
Evo 2003+
Z-Cars (Naturally Aspirated)
GTO 2004-2006
Solstice GXP 2007-09
Cayman S/Boxster Base & S 2005-2012
Boxster S 1996-2004
911 Carrera 2, 4, S and 4S 1999-2008
944 Turbo
Sky Redline 2007-10
WRX (All, including STI)
MR2 Turbo (1989-1995)
Golf R

6. Tuner 4 (T4)

RSX (All)
Integra (All)
TSX 2004-14
TT 1.8T 1998-2006
TT VR6 2003-2006
E36/E46 All, Non-M
328i 2004-2013
CTS V6 2004-2007
Bolt 2017+
Cobalt (NA) 2005-10
500 Arbarth 2008+
Fiesta ST (All)
Focus ST (All)
Mustang V6 2005-2010
Crown Vic 1997-2007
Taurus SHO 1989-99
S2000 (All)
Civic Si 2005+
Hyundai Veloster Turbo T-GDi, TCi GDi 2012+
IS300 2000-2004
GS300 Non-V8 1997-2005
Miata 2006 +
Mazdaspeed 3
Mazdaspeed Protégé
Mazdaspeed Miata
RX-7 Turbo II
3 Touring 2013-2018
Cooper S
300ZX Turbo 1983-1989
Sentra 2013+
Solstice 2006-10
Boxster (Non S) 1996-2004
968 1992-1995
944 1982-91
  Sky 2006-10
SVX 1991-96
Golf GTI 2008+
Jetta GLI 2012+

7. Tuner 5 (T5)

  E30 (Non-M)
  Sonic 2012+
Neon - Naturally Aspirated
Civic/CRX/Del Sol 1972-1991
Civic EX 1992-1995
Accord 1990-1993
Fit 2014+
Prelude 1978-01
Hyundai Veloster Gamma 1.6 GDi 2012+
Miata (Naturally Aspirated) 1990-2005
Spec Miata
RX-7 (1979-1991, Not Otherwise Classed)
Protege MP3
Cooper (Naturally Aspirated)
Impreza 1992 - 2001
MR2 (Naturally Aspirated)