How To Improve Your 4×4’s Fuel Economy

Get More Miles From Every Gallon Of Gas Or Diesel

Most of us find the idea of a compact car owner complaining about the price of fuel absurd. A typical compact car has a 12 to 17-gallon fuel tank, which could cost as little as $30 to fill. By comparison, many modern gas and diesel 4x4s feature fuel tanks that are double that size and cost more than $100 to fill. Of course, larger and heavier 4×4 trucks and SUVs offer more capability than any compact car. Seating, cargo, and towing capacity are all significantly better in a four-wheel-drive truck or SUV. And, most compact cars have zero off-road capability. Although, it can be fun to find out if they do.

All of that capability comes at the cost of fuel economy. As of this writing, the average price of regular unleaded fuel in the US is $2.66 per gallon and diesel is $3.00 per gallon. Some states, such as California, are punished with a much higher fuel price average of $4.17 per gallon for regular unleaded and $4.04 per gallon for diesel. It’s safe to say that pretty much every 4×4 enthusiast is interested in keeping more of that money in their pockets by increasing fuel economy. This is especially true if it doesn’t affect overall on- and off-road performance.

The good news is there are several ways to do just that. And it doesn’t matter what make your 4×4 is or if it is gas or diesel. Read on to find out what modifications and changes you can make to squeeze every mpg from your fuel tank.

A corrected speedometer is essential to accurately measure mpg. Aftermarket programmers are available for the more popular 4x4s. Some vehicles might need to make a trip to the dealership to correct the speedometer for larger tires and gear swaps.

Tire and wheel selection plays an essential part in maintaining fuel economy. Avoiding heavy, luggy, and overly wide tire and wheel combinations will help improve mpg. Even making the switch from a mud-terrain tire to an all-terrain tire will be noticeable.

How Will Correcting My Speedometer Increase Fuel Economy?

Correcting your speedometer after installing larger diameter tires or changing gear ratios will help your drivetrain to last longer and operate more efficiently. Accurate measurement of the distance your 4×4 travels is essential when trying to figure out what kind of fuel economy you’re getting. The addition of larger diameter tires slows the speedometer and the odometer. Increasing the tire diameter from 33 inches to 38 inches results in the odometer being 15 percent slow. Your calculated fuel economy will be 15 percent less than it is. Not even the factory fuel economy gauge in the dash of your 4×4 will be accurate until you correct the speedometer. Several different companies offer aftermarket programmers that can alter the speedometer of your 4×4 to compensate for tire diameter and axle gear changes.

How Do My Tires And Wheels Affect Fuel Economy?

Tire and wheel selection has a significant effect on fuel economy. Lighter tire and wheel combinations will provide better fuel economy than heavier tire and wheel combos. Aluminum wheels are generally lighter and will offer more mpg than heavier steel wheels. Look for lightweight tires with the tread and tire carcass features you need. For example, avoid installing heavy-duty load range E tires on lightweight 4x4s that don’t require that kind of load capacity.

Also, keep wind resistance in mind. Less wind resistance equals better fuel economy. Each tire is like a barn door swinging in the wind when your 4×4 is traveling at 60 mph. Narrow tires and wheels offer less wind resistance than overly wide tire and wheel combos.

Rolling resistance is critical too. Incorrect tire pressure is a common cause of bad gas mileage as under-inflated tires unnecessarily increase rolling resistance. Purchase a quality tire gauge and periodically check and correct the air pressure in your tires. Also, a knobby mud-terrain tire offers more rolling resistance than a less aggressive all-terrain tire. If fuel economy is essential, be sure that you genuinely need mud tires before slapping them on your 4×4.

An open-element cold-air intake is one of the few engine performance mods that can increase performance and fuel economy. The open filter element is proven to reduce intake restriction. Dollar for dollar, there is not a better performance modification.

Big lifts, heavy front bumpers, roof racks, snorkels, and aftermarket lights all increase the wind resistance and decrease fuel economy. If mpg is important, consider smaller components with sleeker designs. Try to reduce wind resistance wherever you can.

What Aftermarket Accessories Will Increase Fuel Economy?

Contrary to some of the unbelievable infomercials out there, few aftermarket accessories will improve fuel economy. In most cases, modern factory air filter boxes and intake tubes are restrictive. They have been proven on many occasions to decrease engine efficiency and fuel economy. The reason is simple as automotive engineers want to protect the paper air filter from water and dirt. They also want to minimizing air intake noise. This is done with a sealed airbox and complex intake tubes. An open-element cold-air intake will free up those restrictions and make more power and better fuel economy. Just remember, horsepower and fuel economy gains depend upon how restrictive the factory intake is.

Aftermarket performance engine tuners can also be used to improve mpg. Many of them feature a fuel economy setting that reduces performance to increase fuel economy. This mode will usually make the most significant mpg improvement on 4x4s with diesel engines and gasoline V8s. Some tuners require premium unleaded, though, which makes minor fuel economy gains a wash.

What Aftermarket Accessories Decrease Fuel Economy?

If a performance part makes more power, usually it will decrease fuel economy. In most cases, you need more fuel to increase power output. Some argue that a supercharger increases fuel economy because you wouldn’t have to use as much throttle. Unfortunately, we’ve rarely seen that to be true. Other aftermarket components that will decrease fuel economy include big lift kits and anything that increases wind resistance. Lightbars, roof racks, larger aftermarket mirrors, chunky front bumpers, and anything that protrudes off of your 4×4 will increase wind resistance and decrease fuel economy. If you want to add these, look for ones with sleek, low-profile designs that don’t hang out in the wind like a parachute.

Driving with your foot to the floor wherever you go is a surefire way to decrease fuel economy. Less aggressive driving and smoother throttle control will improve mpg more than any bolt-on part. Although, it is less fun. 

Remove nonessential items from your 4×4 when making your daily commute. The added weight decreases fuel economy. There is no need to haul around your rooftop tent, camping gear, and snow chains year-round.

Will My Driving Habits Affect My Fuel Economy?

Your driving habits will have more of an effect on your 4×4’s mpg than adding any aftermarket part. The good news is that that you don’t have to be an extreme hypermiler to see mpg improvements. And, changing your driving habits doesn’t cost a dime. The bad news is it can be incredibly difficult for some to drive in the manner necessary to increase fuel economy. To prove a point, we once taped a block of wood under the throttle pedal of a 4×4 that only allowed use of a 1/4 throttle. We saw a significant increase in fuel economy, but it was extremely frustrating (and potentially dangerous) driving slow everywhere.

A better method is to try to hyper mile wherever you go. Avoid jackrabbit starts and frequent stops. Try to maintain smooth and slow throttle control, and you’ll see mpg gains right away. Also, use cruise control whenever possible. It reduces throttle manipulation and improves mpg.

What Other Things Should I Consider To Improve Fuel Economy?

A certain amount of energy is needed to move the given weight of a 4×4. If you can decrease the overall weight of your 4×4, you can reduce the amount of energy and fuel needed to move it. Nonessential cargo should be freed from your 4×4. For example, toting a rooftop tent while commuting daily is a double whammy on your fuel economy. It slaps you with increased wind resistance as well as added weight. Hauling heavy snow chains year-round is also unnecessary. Consider seasonally emptying your 4×4 of items you don’t need. A small weight reduction will improve your mpg only slightly. But removing 500-1,000 pounds of camping and recovery gear from your daily commuter could make a significant difference. And, it will improve acceleration and braking performance.

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