Jeeps were really innovative when they were created... in World War 2. That's when they really were off-road vehicles. The pattern was repeated again with the Humvee, or HMMVW. It's not just converted military vehicles either. It's also race cars and rally cars. Some series have rules that to be legal a car also has to be a production model. Sometimes if you get that exact model you get a race-capable car. But, mostly the cars they sell are variants of the race design, which maintain the fast-looking design, but one which would handle terribly if you put it on an actual racetrack.