> With one diesel engine not being that technologically different from the next how are the independently verified figures of the various other brands working out.

A few months back I heard that VW was pushing for new legislation further lowering diesel emissions to start to remove all its competition from markets. Back then it was rumored that VW had invested in and patented a slightly different direction that worked. Really, you just have to pretend to have succeeded and then cheat to create a monopoly.

Thanks to IP law, there was little incentive for their competition to investigate a system they couldn't use or wager on developing alternative designs given how impossible the claimed results were.

I think VW should be on the hook to meet their current claims while their competitors should not be.