Koopa Clown Car is a vehicle of Bowser, Wart and Dr. Wily. Bowser's Clown Car flies in U directions, Wart's Clown Car has smaller propeller and it performs "ground-pounds" and Dr. Wily's Clown Car has angry face and instead of propeller, fire which shoots fire drops.
A bowser in his car.
A Wart in his car performing "ground-pound"
A Dr. Wily's car. It's different. It has an angry face and instead of propeller, fire.