I know a guy who was using "Home Heating Oil" in his new 1978 Cadillac. After a couple of years, the engine broke down, and he was sad to have used the wrong fuel and messed up the 5.7L diesel. Sure he saved a few cents per gallon, and never paid road tax on that fuel either.
As for electric cars, California now is in the process of taxing electric cars for their use of the roads, without paying the tax that a gas powered car would need to pay. My thought on that is the electric cars are not going to do nearly the damage to the roadways as a 3,000 pound gas car getting 30 MPG and paying only a cent or so per mile to drive the roads. It is the larger and heavier cars that do more damage, yet at the same time use more fuel, and thus pay more tax per mile. THe state is on one hand giving rebates to the electric car buyers, and now thinking that they must tax them to take care of the roadways.
Fred.