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 , with engine design and number of cylinders being free and unrestricted. turbocharging and supercharging was allowed on engines up to a size of .
It was a development and re-labeling of the previous Grand Touring Over (GTO) class. Similar to the original GTO class, the new class rules allowed engines with displacements exceeding , with engine design and cylinder count being unrestricted, and turbocharging and supercharging permitted on engines up to a size limit.