In my opinion, the weakness in the current law is the presumption that motor fuel will be petroleum, a derivative of petroleum or mixed with a petroleum product. Natural gas, butane and propane are covered but I don't see anything on a classic hydrogen-oxygen fuel cell or soybeans that are made by crushing beans. Diesel engines have been made to run on powdered coal dust. There are already hydrogen-oxygen injection mechanisms to mix hydrogen from water with diesel fuel to increase economy. Technically, they probably are not against law since the gas is not mixed with the liquid fuel until an instant before detonation. Who knows?
There was an attempt this year to universalize a tax on motor fuel as any fuel that propelled a vehicle but it was filed under "petroleum tax." It failed because it was attached to a bill to raise diesel and gasoline taxes by two cents.
When the legislature can not write a bill with clarity, they send in the bureaucrats to tell us what they should have passed. Who can trust any of them since they seem to be confused about the permissibility of an income tax and about what the meaning of "revenue/appropriation" is.

Bill,

A clarifying comment. I don't believe the fella in NC is making biodiesel. He is running straight vegetable oil. Otherwise, he would not need any type of additional fuel tank/changeover fuel valve "conversion" on his W123 Benz. If the state wanted to regulate the home brewers of biodiesel from new or waste vegetable oils, they could easily do it in other ways, but I am not volunteering the ideas. The fact is that sales taxes are being paid on the ingredients (in either case). The NC gestapo agents are double-dipping.