Engine? LOL. It's a motor. Engine's run off fuel. All that aside, your choice should consider your budget and what you want to do with your car. If you have your heart set on the TT-01 series of cars, I would choose the TT-01R. Sure it doesn't come with a body or wheels, but it does have the same hop ups as the TT-01D plus adjustible arms, aluminum shaft and alloy motor mount. At least that's what I remember.