If you put that question into Google, you get an answer saying turbo engines have better mpg, but I remember reading that, during the development of Ford’s 7.3L gasoline engine, they came up with some kind of formula that calculated the most fuel efficient engine for a medium duty vehicle was the N/A 7.3 they ended up with. I’ve also heard it from some of my engineer friends. So what is it?
Depends on the engine displacement.