Incidentally, fritz, I don't quite agree with your physics - that's kind of a static 'after things have stabilised' situation.

What I'm talking about is when you are going straight, then you suddenly hit a left bend of a constant radius. You steer, the 12kg mass suddenly moves across the front of thecar, hits the right side of the car and stops. Isn't it more like someone 'dropping' a 12kg bag of potatoes on the side of your car, then removing it? (as the wave of fuel bounces off the right hand side of the car?)...
It's more of a fluid dynamics issue, than a steady-state issue, surely?

Have you ever rocked from side to side in an elevator? How much do you weigh compared to the mass of the whole elevator?...