I consider anything less than a 4 MPG difference to be insignificant. The data on Fuelly suggests that the EPA numbers are largely academic and that your true fuel economy is all up to how you drive and where you drive. Just looking at the model I'm most familiar with, you can hypermile Corvettes if you want, and… » 4/17/14 9:22pm Yesterday 9:22pm

Actually, very many P-40s received Merlin engines, designated P-40L. A great deal more received the much-improved Allison V-1710-81, designated P-40N. The Allison wasn't a bad engine, it just wasn't designed with two-stage supercharging in mind. The P-38 used the Allison mill, and used a turbo-supercharger in each boom … » 4/17/14 7:22pm Yesterday 7:22pm