If you add more fuel you get a bigger bang in the
No incorrect.
What that illustrates is your complete lack of understanding. A car does not skid along the road like a hockey puck propelled by little puffs of fuel explosions like you imagine. Driving down the highway (in high gear) the crankshaft is linked to the wheels directly in such a way that each explosion caries the vehicle exactly the same distance no matter whether you imagine the explosions are big or little. That is if you drive from point A to point B in top gear there will be a fixed number of engine revs involved.
What more power to the piston means is that you get their faster. That is, the piston moves faster so the car goes the same distance in less time. So if you think about what you are saying (obviously, not something you are used to) your claim is that the faster you go (i.e. the more throttle) the better the gas mileage. That is just plain wrong.