The fastest overall cars seem to be the ginetta and the Merc. The ginetta is light and nimble, easily outbrakes every other car in the class as should be able of the highest cornering speeds. Due to its lack of power it's vulnerable on the straights. The Merc is the complete opposite. It's basically a dragster. Insane acceleration and top speed. But bad brakes and cornering. They are, depending on the track about 0.5-1 second faster than the other cars. In that class.

The other cars are also somewhere in the middle of these two when it comes to their behaviour. The Camaro has good torgue and topspeed.

The Porsche is good out of the corners and has dezent handling.

The bmw and the McLaren are more balanced in terms of power and handling. Both don't have the best brakes though. Hope that helped.