Grand Touring Supreme

Grand Touring Supreme (GTS) is the name of a former classification designated to grand touring cars competing in sports car racing, originally by IMSA in the IMSA GT Championship, and later by Grand-Am in the Rolex Sports Car Series. IMSA used the class between 1992 and 1997, and Grand-Am used the class between 2001 and 2003. It was an evolution and re-branding of the former Grand Touring Over (GTO) class. Like the original GTO class, the class rules specified an engine displacement of more than 2.5 L, with engine design and number of cylinders being free and unrestricted. turbocharging and supercharging was allowed on engines up to a size of 6.0 L. Engines over 6.0 L were required to be naturally-aspirated. Between 1995 and 1996 in the IMSA GT Championship, the top GTS class became known as GTS-1, while the former Grand Touring Under (GTU) class became known as GTS-2. This changed again in 1997, when the GTS-2 (former GTU) class became known as GTS-3, due to the addition of a new GTS-2 category, which allowed for existing international GT2 cars, like those used in the FIA GT Championship. IMSA also used the GTS designation for the former GT2 class cars of cars (later known as GT1) in the American Le Mans Series, between 1999 and 2004.