Your explanation of the importance of rotational momentum is interesting and very very clever, but I think you hurried and grabbed the wrong cars in your video when showing the two rotational cases. The motor gears were away from you you so you couldn’t see them. If you look carefully at the video you will see that the wheels and motor turn in-sync and out-of-sync with the cars opposite to ones that you show. If I understand right, the 2-gear design is more efficient and weighs less than the 4-gear. The problem is fitting the 2-gear into the car? Hey, I bet there is some money to be made designing fast cars. Not only a very interesting thing to do, but you could make a comfortable living.