The reason diesel is more than gasoline is they hit it with an additional tax, to make the truckers pay for road maintenance, about 10 years ago.
Yeah, you're right about ethanol. Makes more sense to push for more diesel and biodiesel.
My cousin, a pilot, was complaining about the high price of av gas. They oughta come up with some 2 cycle (lighter weight) diesel engines for private aircraft.
The extra hydrofinishing to make low sulfur diesel shouldn't be very expensive.
Ralph