Piston engines are more efficient than turboprops which are more efficient than turbofan/turbojet engines. Newer piston engines are by far the most efficient o

Piston engines are more efficient than turboprops which are more efficient than turbofan/turbojet engines. Newer piston engines are by far the most efficient option but are not used frequently as the piston fleet is very old. To compare to a car, just using vehicle efficiency (not per passenger) a typical cessna is in the realm of a full size SUV in terms of carbon footprint. Both are about 10-15 mpg. The aircraft in the article is far worse but only because it's rather large and turbine powered. Optimized designs like the Long-EZ can easily hit in excess of 30mpg cruising at 160mph.