My XJ with 5.5'' lift and 32's and 3.55's consistently gets 18-21 mpg out on the road depending on how and what speed I drive. Both of our jeeps do the best right around 65mph. I would just completely go through the jeep. plugs, O2's, fuel filter, etc. Maybe seafoam the jeep and run some injector cleaner through it for a few tanks. FAQ & GLOSSARY. Jeep® vehicles are fuel efficient with competitive fuel mileage. Use the fuel efficiency comparison chart to compare capabilities between Jeep® SUVs. Once the fuel filter was replaced, the mileage increased and ran MUCH better. 2004 Grand Cherokee SE i6 | 2" BB with Daystars and brand spankin' new Bilstein 5100s | Summut Racing slotted & dimpled ultimate performance front rotors and power stop ceramic pads | JK Rubicon wheels w/ 245/70/R17 General Grabber AT2s Search by make for fuel efficient new and used cars and trucks Owner MPG Estimates 2021 Jeep Cherokee FWD 4 cyl, 2.0 L, Automatic 9-spd Regular Gasoline: 2018 Jeep Grand Cherokee TrackHawk 4WD. Personalize. Add a Vehicle. 6.2 L, 8 cyl, Automatic 8-spd, Supercharger. MSRP: $86,200. 2018 Jeep Grand Cherokee TrackHawk 4WD. EPA Fuel Economy. The Grand Cherokee returns 19 mpg in the city and 26 mpg on the highway when equipped with the standard six-cylinder and rear-wheel drive. With the optional 5.7-liter V8, fuel mileage drops to 14/22 city/highway. 2018. 13.2 Avg MPG. 12 Vehicles. 680 Fuel-ups. 162,599 Miles Tracked. View All 2018 Jeep Grand Cherokees. The most accurate Jeep Grand Cherokee Trackhawk MPG estimates based on real world results of 250 thousand miles driven in 19 Jeep Grand Cherokee Trackhawks. For more information about the Grand Cherokee L's fuel economy, visit the EPA's website. 21/18/25 mpg – 2021 Jeep Grand Cherokee L 4x4 V-8 Vehicle Type: front-engine, 4-wheel-drive, 6 Uk6hg.