stored energy, I did not disagree. What seems to be way over your head is Physics, which you apparently did not take, I did. Just because a fuel only has so much energy does not indicate that the machine unleashing that energy cannot do so more efficiently than an other. Read that as the engine that burns more of the fuel and puts it to use rather than one that blows some of the unburned fuel out the exhaust and or wastes the burned fuel in producing heat rather than power.
Still clueless. You are stuck on the non fact that preparative engines were just as efficient as today's modern engines. False False False False False False False False False False False!
The fact that any given fuel can only store "x" amount of energy is off track to your original comment of modern vehicles not being more efficient than those build many years ago.
You have a basic understanding, but are lost with what to do with that understanding.