Claim: GT cars are divided into 2 or 3 subgroups (GT3, GT4, and GT Open), while TC are divided by calculated engine capacity (TC1 - TC4).
Evidence: A grand tourer (GT) is a type of sports car that is designed for high speed and long-distance driving, due to a combination of performance and luxury attributes. The GT abbreviation—and variations thereof—are often used as model names. Several past and present motor racing series have used "GT" in their name . Group GT3, known technically as Cup Grand Touring Cars and commonly referred to as simply GT3, is a set of regulations maintained by the Fédération Internationale de l'Automobile (FIA) for grand tourer racing cars designed for use in various auto racing series throughout the world.