Oh right, that makes sense; constant acceleration implies constant force, and work is force*distance. As the meters tick by more rapidly, the motor performs th

Oh right, that makes sense; constant acceleration implies constant force, and work is force*distance. As the meters tick by more rapidly, the motor performs the same work in less time, and thus the required power increases. Which means, "a reactionless drive is like a car in space" would be a nonsensical concept without a preferred reference frame.