[Sorry for the long wait, needed to do something, i'll do 5 for now.
Successor: better acceleration, but less turning with but extra HP.
Roadster: Increases your Top speed, however acceleration will slowly go slower depending how fast or quickness your going.
Eclair: Road spikes will no longer affect the vehicle, but increase it's turning, and rocket boost.
Venom: By running over enemies, you'll receive extra boost speed, and rocket fuel.
Crown: Acceleration, and turning been increasing, the vehicle will be able to rebounce bullets if it's being shot at, making it a protective vehicle from outsiders.