Kodub, correct me if I'm wrong, but I think since the car actually has areodynamics taken into account, we can say that the higher the speed of the car, the greater the downforce. Thus the suspension is squashed and your car rides literally 0.000001 pixels above the ground (an exaggeration). So the hitbox of the car's chassis hits the road piece before the wheel's suspension can lift the front end causing the car to take flight. (sorry if my explanation is hard to understand, i'm trying to improve it)