Fight on, Wetzel, you have them on the run!
Not really. Here in Michigan, and I'm sure in other states as well, you can buy fuel for farm use and you don't pay the excise tax for road maintenance on it. But you're not allowed to use it in a road vehicle, only farm vehicles that don't use public roads.
So, if you're allowed to skip the fuel tax if you don't use the fuel on the road, then you should have to pay the tax for fuel you do use on the road, even if you got that fuel from the McDonald's fryer.