A childhood belief about cars

I used to believe that the speed of our car depended on how strong my father’s legs were. I thought that we went uphill more slowly because he couldn’t press the gas pedal hard enough. I now think I’d made an analogy with the brake pedal. Once, our crowded car stalled while going up a hill and my dad said something like “The engine’s not up to this.” I was very puzzled because until then I’d thought that the engine’s job was just to amplify my father’s effort. I asked him about it, but it took several questions and a looong time for him to understand me.