I have a variety of improvements, but most people don't have the dedication to enact them. Chiefest is to change the transmission ratios in the manual version, then put in the 2.62 rear end to slam highway RPM's to 838 from 1800. That would yield at least, by the diesel engine industry's reckoning, 9.62 percent better mileage with no other changes. Then, there are aerodynamic changes, etc.