I recently bought an '07 Grand Cherokee limited, 5.7l hemi. Getting into this, I knew I was gonna be taking a hit on gas mileage going from my 2.5l Altima, but I didn't realize how bad it was going to be. The jeep is a daily driver for me, commute to work is about 15 miles, and I'm getting 12.5-13.5mpg right now. This is absolutely killin' me, and I'm wondering if anyone has any suggestions on how to improve this number. I don't have a lead foot, I set cruise control, I do everything I can. Any ideas or suggestions would be greatly appreciated.

 

Lower the front suspension and raise the rear suspension, that way you're always going down hill. I think you're stuck with the crappy mileage, you could try running 35psi in the tires and taking the roof rack cross bars off. Run a lighter oil in the engine, like a 5w20. It is a huge shock to go from 30mpg to less than 15 on the highway, but at least you're more comfortable and able to explore off road.

 

For a V8 engine this is about right, could be a bit better. You can always clean out the intake throttle body assembly (many videos on YouTube that show how to do this) Also, change the spark plugs, wires, fuel filter, and get a fresh oil change with new air and oil filters.

That should bump you up 2-3 mpg I am guessing. Also, clean the MAF sensor as well. The throttle body gets heavy carbon residue buildup so clean it every 20,000 miles or so

 

I have a 94 with the 5.2 and get 15 to 17 steady over several tanks of fuel. Wasn't that good when I got only 12 or so.. I cleaned the intake body assembly, SeaFoamed the engine twice an cleaned the injectors.. picked up a clean 4 to 6 mpg and as a side benny it rums better... I have 204000 miles and running strong. Knock Knock on Wood.. LLLOOOLLL