I used to own a 1959 Saab automobile. I had a 3 cylinder 2 cycle transversely mounted water cooled engine. When using the standard "free wheeling" function and traveling on the equivalent of the Interstate highways I routinely enjoyed 50 mpg fuel economy. I could also "get rubber" from all 3 gears when in the alternate gearing system (just like a standard shift). This was a great little car, but was superceded by a Saab vehicle with a 4 cycle engine. I cant afford a Saab anymore (I was in college when I owned the former one), but I wonder why the vaunted aircraft engineers ever gave up on making the efficient engine of the past.