Guess what? We’ve got bad news for you. Driving a Jeep built to go off-road is a sure-fire way of getting bad mileage. Why is that? Well it’s just a fact of life. If you want to get good fuel mileage there are a few things you can do…but unfortunately, none of them fit too well with any Jeep that actually gets used off-road. First you can drive a small aerodynamic car. Hmm…Yep, most Jeeps are large and have the aerodynamic profile of a brick. Smaller tires with efficient tread patterns and lower rolling resistance can help to increase mileage. Big, heavy, durable, blocky tires with massive treads suck down the dinosaur spirits for sure. Poop! Lightweight cars with lightweight modern chassis are the way to go for efficiency. Even a relatively lightweight XJ with Unitbody construction will have to be stiffened (Read: add weight) to get it to last more than a few years off-road. Two-wheel-drive cars generally get better mileage. Good luck getting a two-wheel-drive Jeep over Hell’s Revenge or the Rubicon Trail. Yep, we can’t win.
Things only get worse from there when you try to make your Jeep safer, more reliable, and more comfortable. Rollcages add weight, as do spare parts, tools, bigger fuel cells, fancy seats, winches, bigger tires, additional lift, etc. Ugh. Now we feel really sad. Weep. Adding power to your Jeep’s engine can sometimes lead to slightly better fuel economy, but not always. So what’s a Jeep enthusiast to do? Well, here are a few aftermarket gizmos that we have had luck with, and a few tips and tricks that may also help keep you away from the pump as much as possible. But remember, unless it’s free (like checking your tire pressure) or something your Jeep needs anyway (like a tune-up) it’ll generally take an unrealistic amount of time to recoup the cash outlay in any increase in fuel economy. Bottom line? You gotta pay to play and unless you wanna trade in your Jeep for an econobox (not likely or advisable) you just gotta get happy with the notion that economy is relative to what you get in return. Till then, good luck and may we suggest looking into selling some blood.
It’s probably not news to you that allowing your Jeep to breathe more freely with a high-flow air intake system or at least a high-performance replacement air filter can yield a slight boost in power and mileage. It makes sense doesn’t it? What’s best for your Jeep and your Jeep’s fuel economy is lots of cool (denser) air. Often times factory air intake systems are compromised for the sake of minimizing air intake noise. Aftermarket intakes forgo the concerns of getting rid of that extra noise for maximum power and efficiency.
Estimated Improvement: 1.0-2.0 mpg
Exhausting All Your Options! Har, Har!
So now we are getting more air into the engine, how about letting it out. That’s an old hot rodding trick that can work for your Jeep as long as you don’t get carried away with the tubing diameter and kill your exhaust gas velocity, which will decrease cylinder scavenging and can have an adverse effect on power and mileage. Again, these aftermarket systems generally make more noise, but most are not too obnoxious. We have heard the theory that all this extra noise can bring out your inner Mario Andretti and cause lead foot syndrome. That’s bad for fuel economy.
Estimated Improvement: 0.5-2.0 mpg
Tune It in Turner
Keeping your Jeep’s engine in tune is key to economy. That means maintenance, clean air filters, properly gapped spark plugs, fresh oil, and clean fuel filters and intake/carb/throttle-bodies. According to Editor Hazel, advancing engine timing just a little can often help improve fuel economy, and Trasborg recommends keeping oil off your Jeep’s O2 sensors. This will allow them to work more efficiently. Also, O2 sensors can wear out and should be changed if fuel economy suddenly plummets or if the old ones have much more than 100,000 miles on them.
Estimated Improvement: 0.5-4.0 mpg
You Drive Like a Grandma
We hate the term “Jack Rabbit Starts” every time we hear it, but it is descriptive…we’ll admit that. If you are constantly flooring your Jeep when the light turns green in some imaginary drag race with the shmo in the car next to you (like us), or if every highway onramp is your own personal runway where you have to reach 88 mph to get back in time (like us), then you will get horrible mileage. But driving like your grandma will save you cash at the pump. Another descriptor we have used is drive like you’ve got an egg on the dashboard and you don’t want it to fall off. Just be ready for a Jeep with Jp stickers to pass you by, sucka! We’ll laugh at you—until we have to stop to buy more gas.
Estimated Improvement: 0.5-1.5 mpg
Wench on a Diet
Weight watching is gonna be one of the best ways to improve or regain lost gas mileage. We were able to save about 30 lbs by switching from heavy steel cable and a steel roller fairlead to a synthetic winch rope with an aluminum Hawse fairlead.
Estimated Improvement: N/A
Low-Down, Dirty Sons of a….
…biscuit. We’ve been saying it for years; generally Jeeps that are low to the ground work better off-road and feel more stable and safe. Bigger, taller Jeeps with huge lifts may look cool (maybe to you), but they do get worse gas mileage because they are pushing more air down the road. Drop that Jeep down and cut some body away to clear those tires instead. Actually, this is sort of in the same vein as adding an air dam to limit under-chassis drag, but immeasurably less goofy and actually something we’re down with.
Estimated Improvement: 0.1-0.5 mpg
It’s Not the Size That Matters…
It’s how you use it. That’s what someone said. Bigger wider, heavier, gnarlier tires don’t help your Jeep get better mileage. Big tires are cool, but it is possible to have fun with stock size tires too. If your Jeep is your daily driver and you’re considering selling it to step into an econobox, you can take the cash you would’ve spent on big tires and wheels, a fancy lift, and new axle gears and instead buy lockers, a winch, and lots of extra fuel. Jeeps with stock-sized tires are gonna get better mileage and be easier on drivetrain parts. Another option would be to watch tire and wheel weights next time your Jeep needs new shoes. Maybe those gnarly 33x13.50/15 bias-ply tires can wait and instead you can get some 33x10.50R15 radials. Lighter wheels and tires require way less fuel to get up to rolling speed, which can really save at the pump if you do a lot of stop and go driving.
Estimated Improvement: 2.5-4.5 mpg
Synthetic fluid can help boost mileage just a little if you’re able to drop the viscosity of the oil you are using. Thanks to synthetic’s superior lubricating and filming qualities you could, for example, go from 15W40 down to 5W30. The lighter-weight oil, coupled with the somewhat slipperier synthetic, will create less drag on the engine’s reciprocating components, which frees power and mileage!
Estimated Improvement: 0.1-0.5 mpg
Is your Wrangler outfitted with enough trail armor to make some military vehicles look wimpy? That extra weight may keep your sheetmetal straight (not that anyone could see it under all that steel armor) but its adding weight and massively hurting your Jeep’s mileage. Man up and take the body damage. An alternative is to look into what a certain part may weigh and see what other options are out there. Aluminum? Yep many parts are now made out of that stuff. Is it cheap? Nope! But it’s not that much more cash. Tube? Yep, we saved weight by switching from bulletproof flat steel rocker guards to a set of homemade tubular rocker guards on our TJ. We figure we have saved about 30 lbs over the plate version. Not a ton, but in the long run every little bit helps!
Estimated Improvement: 0.5-0.7 mpg
Imagine Forest Gump running down the road. Is he: A) Using less energy while running and wearing baggy MC Hammer-style pants and big fat down coat, or B) while wearing a smooth, tight-fitting synthetic track suit? The same is true for your Jeep. A Wrangler with a hard top and hard doors will get better mileage than a Jeep with a soft top a-flappin’ and a-poppin’ in the breeze.
Estimated Improvement: 1.0-1.7 mpg
Bugs in Your Grille
Often a Jeep with smaller grille, for example an XJ rather than Wrangler, can get better mileage. Again, this is because of aerodynamics. Big, flat sheets of metal with seven slots cut in them are less aerodynamic than smaller sheets of metal with seven slots cut in them while hurtling down the highway. But other than buying an XJ for your commuter there’s really nothing you can do about that…so why the hell are we even talking about this here. San Dimas High School football rules!
Estimated Improvement: N/A
Take Off Your Top!
It’s no secret everyone likes going topless. It lets those amazing wonderful parts of your body tingle in the passing wind. Hello! Honestly, not to be the bearers of bad news, but running any top verses no top at all on your Jeep will help you get better gas mileage. It cuts down on turbulence and helps improve the aerodynamics of your already horribly non-aerodynamic Jeep. So if you normally run with no top at all or just a bikini top, tossing on the ol’ soft top for those longer freeway trips can increase your aerodynamic profile.
Estimated Improvement: 0.5-1.0 mpg
Damn You Air, Damn You!
One way to increase fuel economy is to cut down on turbulence. Just in case you had not noticed there are lots of bumps, bits, widgets, frammises, and humps hanging out the underside of your Jeep. If you could, and honestly you probably won’t want to, you could add smooth body fairings to the belly of your Jeep, or add one of those fancy front air dams like on the import-tuner at the stop light next to you. These parts will reduce under-chassis air turbulence and drag and increase fuel economy. Plus think how rad your Jeep will look until you go wheeling again and break all that dam stuff off.
Estimated Improvement: 0-0.5 mpg
Seven Other Ways To Save Fuel:
1. Leave that Hi-Lift jack at home when you are driving the Jeep to work. If you use your Jeep for commuting dress it down for the weekday.
2. Look into a set of smaller, lower rolling resistance tires with lightweight wheels and get good at swapping them out. Pull that winch off. Ditch that rack with cooler and gas cans.
3. Carry an air compressor or CO2 tank and a plug kit rather than a spare tire and wheel and pray you don’t cut a huge gash in your sidewall.
4. Have beadlocks and on-board air? Bring a plug kit and a spare tire minus the wheel.
5. Attach a block of wood to the back of your throttle pedal. If you can only press the pedal half way you should get better mileage. Just don’t forget it’s there and pull out in front of that angry Mack truck.
6. Use the overdrive gear on the highway. If your tires are too big and Fifth gear doesn’t work it’s time to consider new axle gears.
7. Lastly, and we are not sure why we are suggesting this cause it means we will probably have to test it out, check with your local law enforcement and see if it’s legally okay to ditch the windshield on your topless Jeep for some goggles or sunglasses. We bet your gas mileage will go up.