[MosesKnows]

if memory serves

I think your memory is faulty, by several times. There is considerable difference between gasoline and diesel fuel and there there is considerable difference between a gasoline engine and a diesel engine.

[Abathar]

"The makeup of both gasoline and diesel is different as well. Gasoline is typically C9H20, while diesel fuel is typically C14H30. The increase in carbon and hydrogen atoms is the reason the energy density of diesel is greater as well. On average, 1 gallon (3.8 L) of diesel fuel contains approximately 155x106 joules (147,000 BTU), while 1 gallon of gasoline contains 132x106 joules (125,000 BTU). "

I have both diesel and gas vehicles, I thought the BTU ratio per volume was even higher than what this site states, that is what I was referring to.