Vw tdi ??

I don't know about other states but thats illegal here in MN. Lord help you if you ever get caught doing that.

Operating a vehicle with dyed (untaxed) fuel is usually frowned upon in most states. Here in MI, it used to be grounds for losing one's Concealed Pistol License (I can't find it on the list anymore, but operating a locomotive while under the influence will still cause a CPL to get yanked).
 
The Audi wagon rental I drove while there got almost 70 mpg. We could do the same here if the took some of the pollution BS off the cars.

It's not so much the emissions crap, as the EU will soon be adopting a newer regulation similar to the US's. VW/Audi's w/ the BlueMotion technology can accomplish this. I just wish they'd bring it over here. That shit would sell like hot cakes!