Jim is on point here, overpower does seem to be the best route especially if your vehicle has disadvantages to start with. I had a '78 Chevy 3/4 ton 4X4 Suburban that originally came with a 350. All it was capable of was around 11 or 12 mpg at best on the highway. 2 years later, I dropped a bored out 400 sm block in it and the mileage jumped to almost 15 mpg. The more horsepower it seemed helped push the 5800 lbs down the road with less effort, hence less fuel consumption. As for a small vehicle like a CJ tho, I dont know where the point of diminishing return would be. I have heard that all the engines (4, 6, and 8) are pretty close in mileage ratings. You just cant escape that flat faced front end! Altho you have a 4 cylinder, the gearing installed to apply the power to the wheels prevents the mileage benefit. About the only way you can realize any more mileage with your set up would be to find an overdrive unit to use while cruising at highway speeds. If you plan to put bigger tires on, forget that, you will be constantly shifting out to climb hills. Jeeps are not designed to be fuel efficient, they are designed to be fun! Since the EPA got involved, they have started to try to do something about the problem. Thats why you see EFI's, 5 speeds and more aerodynamic shaping in the newer models. <img src="/forums/images/graemlins/notooth.gif" alt="" />