911 GT3 RS: This is the limited-edition homologation of the 2007 GT3 RSR race car, built to meet FIA GT rules. Rumors are the race car and the RS will get the 3.8-liter flat-six, instead of the 3.6-liter engine. The RS is a lightweight car with the Carrera 4's wide rear fenders, a wider rear track, more aggressive wing, and modified front spoiler lip. Weight savings include a carbon-fiber wingtop, lots of composite bodywork, and lightweight glass.