I don’t think it’s possible to make Hummer H3 go 60 miles per gallon through drivetrain mods, no matter how many turbines or supercapacitors you put in. Aerodynamics simply isn’t there.
For many modern cars, 50 mpg highway is the limit. For SUVs, it’s less.
But you can achieve a lot more if you couple drivetrain mods with some sensible exterior mods:
