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1 2022 4Runner TRD lead 1

How to Improve Fuel Economy in your 4×4

From mild to wild: Upgrades to squeeze the most out of every drop of fuel

Photography courtesy of manufacturers, Harry Wagner & The Dirt Staff

Fuel prices have skyrocketed over the last few months and even though 4×4 vehicles have come a long way with how many miles you can get out of a gallon of fuel, your typical 4×4 still leaves a lot to be desired, as far as fuel economy goes. It’s hard to argue against multi-speed transmissions, direct injection and aluminum body panels but we think there’s still room for improvement. Here are a few ways you can improve your 4×4’s fuel economy to help you get the most smiles and miles. 

2 1997 Jeep TJ 1

At best, the 1990’s Jeep Wrangler could average a mixed fuel economy of 17 in the city and 19 on the highway unless you had the 4.0L, which could put you as low as 13 in town and not much more on the highway. 

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Today’s EcoDiesel Jeep Wrangler averages 23 in the city and 29 on the highway.

The Hard Truth

The best thing you can possibly do to get the most efficient fuel economy out of your 4×4 is leave it alone. Don’t lift it, don’t put different wheels, or bigger tires on it, just wheel it. Anything you do to your stock vehicle will alter how it was designed in the factory and in return will decrease your fuel economy. But – that’s not what most of us will do. Whether it’s just another Jeep or 4Runner, most of us want to put our own touches on it, to make it unique and make it ours.

So you’ve modified your 4×4 and your fuel economy dropped, what can you do?

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Proper Tire Inflation

The easiest and cheapest upgrade you could make to improve your fuel economy is top off your tires with air to the recommended tire pressure. If you’re driving on the highway with less than the recommended air pressure, you’re not getting the best fuel economy out of your tires. Remember, when you air down, you are gaining more traction and a wider footprint which is great off-road but on the street, it only adds more parasitic drag to your 4×4. 

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Regear Your Axles

If you’ve put bigger tires on your 4×4, odds are your speedometer is off now. That’s an easy way to tell if your ring & pinion gears should be upgraded to reduce the strain on your drivetrain. The purpose of regearing your axles is to reduce how hard your engine has to work to get your tires spinning.

If you go from 33-inch tires to 37-inch tires on your Jeep, you’ll end up sacrificing low end torque and forget about ever seeing overdrive ever again. The only way to correct this is to regear your axles. If your factory gears were 4.10’s, you’re going to want to go with a 4.88 gear to compensate for not just the added tire size but also the added weight of your new wheels and tires. 

On older 4×4’s with 31-inch tires and anything close to a 3.50 gear that you’re bumping up to 35 inch tires or more, you’re going to want to consider at least 4.10 gears if you don’t have an overdrive transmission or a 4.56 gear if you do or if you wouldn’t mind having a little extra torque down low. Doing this will get the RPM range back within its stock range but keep in mind that heavier wheel and tire combos might require a little more lower gearing to move down the road comfortably. 

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Air Filter & Intake

Making sure you’ve got a clean air filter is another good step to take to improve your fuel economy. There are plenty of aftermarket intake options, some are better than others and advertise up to 3-5 MPG of fuel economy gains. There are even a few options that will drop right into your factory airbox location if you’re simply looking for a replacement air filter. 

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Aftermarket Exhaust

Car manufacturers have really stepped up their game in making sure that exhaust systems are efficient, and don’t hinder the performance of your 4×4. The exhaust that comes on your truck does weigh quite a bit however, and let’s be honest, most don’t sound the best right out of the factory. Replacing your exhaust with an aftermarket unit will definitely reduce the weight of your vehicle and make it sound way better. As far as fuel economy goes, it’s not always the case unless you’re replacing an exhaust on your 15+ year old car.

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Computer Programmers

If you’ve got a diesel powered truck or jeep, or a turbo-charger on your gasser, a computer programmer is worth the return on investment. Most of the time the increase in fuel economy will be minor but it should be noticeable and you will also feel the difference in throttle response. If you have a naturally aspirated gasser, at best it’ll just recalibrate the factory throttle response and give you full control over when the throttle blade cracks open and once you get your fix of snappy throttle, you’ll likely ween off it and use it sparingly rather than constantly drive it like Ricky Bobby.