Naturally aspirated engines also rely on the density of the atmosphere for their efficiency. At sea level, they produce full power, but as you go up in elevation they decrease power substantially. It's pretty much impossible to sustain combustion alive 12,000 feet without using a turbocharger or a supercharger. While that's not necessarily a major problem for cars, it's a huge problem for airplanes with reciprocating engines. There are lots of small aircraft with turbochargers as a result.