The GT, or Grand Touring, class has long been a staple of sports car racing, both in national and international competition. The cars are historically those production-based cars built from the street and modified for the race track, though some cars in international series have been built as specificbased race cars with production-lookalike bodies.

GRAND-AM has employed a two-class system for the Rolex Series since 2005, running Daytona Prototypes and GT cars.

Currently, the Rolex Sports Car Series GT class sports some of the top models of sports cars in the world, with competitors adhering to GRAND-AM’s level-playing field. Among those cars eligible for competition in the Rolex Series GT class are the Audi R8 GRAND-AM, BMW M3 and M6, Chevrolet Camaro GT.R, Chevrolet Corvette, Ferrari 458 Italia Grand Am and 430C, Ford Mustang, Infiniti G Sedan, Jaguar XK8, Lamborghini Gallardo, Mazda RX-8, Mercedes-Benz SLS, Nissan 350Z and Porsche GT3.

GT cars competing in the Rolex Series can be unibodied production cars (Prep 1) or custom tube frame chassis (Prep 2). The rules for GT employ several methods of equalization, including race car weight, tire size and engine RPM limits to provide an even playing field for the variety of different cars. Engines in GT machines produce between 390 and 450 horsepower depending on the car.

The GRAND-AM Rolex Sports Car Series ran multiple GT classes from 2000-2004, including GTU, GTO, AGT, GTS and SGS.