> If the engine cuts the weight of the car in half Then this engine has negative weight because current engines are much less half the weight of the car, let a

> If the engine cuts the weight of the car in half Then this engine has negative weight because current engines are much less half the weight of the car, let alone half the weight of the car plus typical load (which is the relevant weight). Yes, an engine that weighs less means that you can have other parts that weigh less as well, but it's still not enough.