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Gas Sucks - Get Better Mileage

Custom Jeep Buggy
Verne Simons
| Senior Editor, Jp
Posted April 1, 2013

Squeeze Every Yard Out Of That Gallon

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.

Better Breathing
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

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