Under the technical rules of the ACO, two categories of sports car prototypes ("LMP1" and "LMP2") as well as two GT classes ("GT1" and "GT2") compete for victory in the Le Mans 24 Hours and the LMS. LMP1 and GT1 are primarily intended for works teams, LMP2 and GT2 for private teams. Since Porsche places such great emphasis on customer motor racing, the RS Spyder is an LMP2 sports car, while the 911 GT3 RSR is classed as a GT2 vehicle.

Both Porsche racecars have been adapted to the changed rules for the 2009 season and the 911 GT3 RSR in particular has been enhanced.

The most obvious change to the 2009 enhanced 911 GT3 RSR is the redesigned front section with large ventilation openings on the bonnet. The louvers, as they are known, hint at the completely revamped air guide on the radiator, which had to be redesigned due to the rearrangement of the outgoing and supply air when installing the optional air-conditioning system. The aerodynamics in the lower rear area, the adjustment area of the rear wing and the weight of the brake system and wiring harness were also optimised. Due to the requirement for a further reduction in the size of the air-flow limiter, the 4-litre flat engine generates roughly 450 bhp at 7,800 rpm and delivers a maximum torque of 430 Nm at 7,250 rpm.

Following the significant reduction in the size of the prescribed air-flow limiter called for under the rules, the 3.4-litre V8 engine of the RS Spyder now generates 478 bhp instead of 440 bhp. The rear wing and the underbody have also been adapted to comply with the changes in the rules.