Why do larger engines get less MPG? Couldn’t a V8 be geared to a lower RPM and consume the same or less than an I4 at a given speed?

Question

I imagine some of the difference is due to weight (larger engines being in trucks) or performance (sports cars made to accelerate rather than cruise well), but it seems that almost without fail the bigger the engine the less MPG, I don’t understand where the extra energy goes if not to the wheels

In: Engineering

Answer 1

There is a lot of energy wasted moving pistons up and down and turning a heavy crank, extra cans, valves, timing chain, etc.

Just look at the improvements in efficiency eliminating pushrods, just a small rod that goes up and down… millions of times.

Smaller, lighter, fewer moving parts is more efficient.