◊Definition of a Grand Touring Car
It is an automobile having at least 2 seats and one door on each side respectively for getting in and out of the vehicle.

◊JAF-GT vehicle qualifications
The cars must be homologated to FIA Group N, A, GT2, GT1, JAF Production Touring Cars or Special Touring Cars regulations, or otherwise be registered with JAF as approved vehicles.

◊ Qualifications for 4-door car use (GT300)
Only 4-door car s that do not have a 2-door model in their model family can be used.

◊Composite materials (Including carbon and kevlar)
Composite materials are permitted in the relevant parts or areas if authorized in the regulations, or used as standard on the original car and original engine.

◊Titanium and ceramics
Apart from connecting rods, intake and exhaust valves, valve retainers, heat shields, brake caliper pistons and superchargers, titanium and ceramic materials can be used on specific areas of the car, but only if these materials are used as standard on the original vehicle and engine.

◊Control function restrictions:
Any automatic or electronic chassis control system or function is forbidden, even if standard on the original vehicle. A simple open-loop electrical switch activated by the driver acting on a system such as for opening and closing the windows is not considered to be an electronically controlled system.
Areas designated “free” in the following regulations are still subject to the above regulations.

◊Type and position of engine:
An engine that is produced by the original manufacture and is legal for road use and approved by FIA and/or JAF can be mounted. The mounting orientation, direction and location of the engine are without restriction provided the engine is situated within the engine compartment of the original vehicle.

◊Position (GT300)
There are no restrictions on the orientation/position of engine mounting.

◊Engine modifications:
Modifications to cylinder capacity are permitted. Supercharging devices are also allowed. Modifications to camshaft position/number and changes to the driving system are not permitted. Intercoolers for cooling the intake air including its mounting position and piping are unrestricted. The exhaust system is also without restriction. However, no types of variable exhaust systems are permitted. Supercharging is not allowed when a 3-rotor engine is used on a GT300 vehicle.

◊Limitations on engine use (GT500)
Only one engine can be used for each race week (from the day before the qualifying to the race). If the engine is replaced during this period, the team's starting position will be dropped ten positions from the grid position earned in the qualifying.

◊Shape and mechanisms of air restrictors
All cars must have either 1 or 2 air restrictor(s) made of metal with parallel hole(s) having circular cross-section maintained with a minimum length of 3mm. All air feeding the engine must pass through the air restrictor(s). When all intake air is closed off upstream of the air restrictor(s), the engine must stall immediately.

◊Minimum vehicle weight
All cars must have the minimum weights shown in the accompanying table. These represent the minimum weight of the car in running order and they include all lubricating oil and cooling liquid filled and exclude the weight of fuel and the driver. During competition the weight of the vehicle must never be less than the minimum weight. Handicap weights and their attachment device weight are not included in the minimum weight.

†GT500 car performance adjustments (GT500)

• The minimum car weight for the NISSAN GT-R, and LEXUS SC430 is 1100 kg.
• The minimum car weight for the Honda NSX is 1150 kg with the restrictor at the same setting as with the 1100 kg minimum car weight.
• As a GTA Special Approval car, the NISSAN GT-R has been allowed to adopt some of the 2009 JAF-GT regulations based on GTA judgment.
• For these three cars, performance adjustments will be made based on the results of rounds one and two of the 2008 series to be applied from the second or third round. As a rule, this type of adjustment will be made only one time during a season.
  This weight adjustment is a car minimum weight adjustment and is not reflected in the restrictor scale. (The details are in the 2008 GTA Bulletin 004-T)

◊Stepped Bottom (GT500)
A minimum ground clearance of at least 60 mm must be maintained. However, a skid block of 200 mm in width and 30 mm in thickness must be mounted under the floor on the wheelbase span and this skid is not subject to the 60 mm ground clearance regulation. Also, the skid blocks may never be worn down more than the amount specified in the regulation.

◊Overhang (GT500)
The overhang of the front under-plate can be extended to as much as 115% of those of the original vehicle as long as they do not exceed 1,020 mm. The length of the underside of the rear bumper can be extended to as much as 115% of that of the original vehicle as long as it does not exceed 1,060 mm.

◊Windshield and Windows
The front windshield must be in accordance with the rules under "Safety regulations for homologated cars and registered vehicles" in the JAF regulations. The front windshield glass may be replaced with polycarbonate of a thickness greater than 6mm and which permits the cockpit interior to be visible, provided the same installation position and shape as the original glass is maintained.

◊Bodywork
Composite materials and light metals may be substituted for the front and rear bumper, fender, door, bonnet (hood), rear hatch gate and trunk lid components provided that these substitutions maintain enough structural strength and do not result in configurative changes. Louvers, ribbing or lips etc. may be installed, if they do not significantly alter the external appearance of the vehicle (maximum protrusion allowed is 20mm).

◊Body structure
The cockpit area must not differ from the original vehicle specifications (monocoque structure). Regardless of the number of seats in the original model, a bulkhead can be added behind the front seat. The body components behind that can be replaced by a tubular structure.
Main structure (structural framework) situated fore of the front bulkhead and hind of the rear bulkhead may be cut and replaced by a tubular structure that is connected to the rollcage. In this case, it is obligatory to install a crushable structure defined under the regulations.

◊Fenders: On each side of the car, fender dimensions may be extended (increased in width) up to 5cm over the width of the original vehicle, but the maximum width must not exceed 200cm. The front part of the front fender and rear part of the rear fender must fit within the area defined under the regulations as viewed from above.

◊Hard tops for open-top (convertible) cars
Hard tops may be installed for open-top cars. But the hard top must have a configuration similar to the original. Use of material is unrestricted.

◊Front aerodynamic device
The front bumper may be integrated into a front aerodynamic device in its construction. The integrated bumper and aerodynamic device must not be mounted higher than 250 mm above the flat bottom and must be farther forward than the center of the wheel rotational axis of the car in running specification (the car as presented at all the car scrutineering sessions).
The lower structure of the bodywork may be connected to the lower part of the fender which is situated forward of the vertical plane passing through the foremost point of the front complete wheel. There are no restrictions on materials used for front aerodynamic devices.

◊Rear aerodynamic device:
It is permitted to fit either a rear air spoiler or a rear wing. The device on the original vehicle may be changed or removed. The wing must comprise no more than one aerofoil section and shall have dimensions that are not to exceed 33 cm x 15 cm (including gurney-flaps but excluding supports and end plates) when framed in a rectangular side-view. Its height must not exceed the highest point of the transparent part of the front windshield (including sun shield etc.,). Its width must not exceed the maximum width of the original vehicle (including supports and end plates). The position of the rear edge of the rear wing must not exceed 1,060 mm from the center of the rear wheels and it can be moved back to a position equivalent to 115% of the original model's rear overhang.

◊Diffuser (aerodynamic device mounted to the underside of the rear floor)
It is permitted to add a completely flat inclined panel (diffuser) without openings. The inclined panel must be placed between the vertical planes passing through the rear edge of the flat bottom and one passing through the rearmost point of the bodywork. Maximum width of the panel must be within 650mm to the right and left of the longitudinal axis of the car and it must be symmetrical. No part of the panel may be situated more than 150mm above the flat bottom. If there is a gap between the inclined panel and the bodywork, it must be closed by a panel (shielding) vertical to the ground.

◊Flat bottom
It is obligatory to install a flat bottom over the entire width of the car as viewed from underneath excluding the wheel housing and outer rear view mirrors. Between the front and rear wheel centerlines, a strong surface shall be securely fitted to the underbody of the car. The flat bottom shall not have any aerodynamic effect and no air stream may pass between the floor of the cockpit and the flat bottom. It is permitted to have an upwardly curve at the perimeter of the flat bottom as long as the radius of the curve does not exceed 25 mm .

◊Side skirts:
Side skirts are permitted below the horizontal plane passing through the centerline of the front and rear wheels of the car in running order as long as they do not extend beyond the maximum vehicle width. The front/rear edge and the lateral edges must have a radius of more than 5mm. The outer surface of the side skirts may not enter the inside of the outer surface of the original vehicle. Furthermore, they must be connected to the flat bottom without any openings or gaps, and must also be connected to the front/rear fenders. There are no restrictions on side skirts materials.

†Under Technical regulations, the use of carbon brakes is permitted. However, under race regulations their use is restricted, so decisions will be made on the basis of the type of model and the conditions of the machine.

• Complete wheel maximum width for GT500: 14 inches / GT300: 12 inches
• Complete wheel maximum diameter: 28 inches (GT500 and GT300)

◊Headlights:
Headlights must retain the same configuration and function as on the original vehicle and they must retain a brightness that can be recognized when lit. The main optical axis must be to the front. It is permitted to alter the light source for the purpose of increasing illumination (or luminous intensity). If the vehicle is originally equipped with retractable headlights, the retracting mechanism may be removed and modifications made to have the headlights light the road ahead as usual. Headlights that can flash sequentially with the right and left lights are prohibited. Headlights installed on GT500 cars must have white and GT300 cars must have yellow or amber colored covers.

◊Tail lights, brake lights , turn signals, etc.
Tail lights and brake lights must have the same configuration as those of the original vehicle. Brightness (light intensity) of these lights must be equal to or greater than that of the original lights. Ducts can be connected to openings that are created by the removal of other original light assemblies.

†This item is also listed in the race regulations.