The GTA rules are intended to allow competitors to use proven stock-car technology to compete in SCCA road racing events at a reasonable cost. The philosophy of GTA is to provide opportunities to build a car from readily available stock-car parts.
The rules allow a variety of chassis and body styles with different weights depending on the combination chosen, but the basic guidelines of the class are “about 500 horsepower in a car weighing 2800 pounds and competing on readily available bias-ply racing slicks”. The class originated with stock car bodies but now includes later generation Camaro, Mustang, and Challenger bodywork as well. The horsepower and tire limits make for extremely close competition while keeping costs relatively low.
Full ruleset GCR search phrase – “GTA Category”