The rotating ball should push the vehicle first to the right and once it hits the airbag - to the left?? Even if this works, how are you going to automate it and repeat it?
Correct. You can't reset it without reversing the motion. The vehicle might rock back and forth, but it will not make any progress. You can make it ever more Rube-Goldbergian, and have the passenger supply the energy into moving it, but that's just an inefficient human-powered machine.
BTW, such perpetual motion discussion is a forbidden topic on PF, so I expect this thread won't be open long.
Yep, thread is closed, not because it's a PMM, but because we don't support discussions of "propellantless propulsion" with a violation of the Conservation of Momentum.