Maximizing Fuel Economy

Improve fuel numbers, lower operating costs; it’s not as easy as you think

by Bruce W. Smith / ProPickup

Sit in on any jobsite conversation in the country where pickups and performance are the topic and once the my-truck-will-out-pull-yours bravado settles down the conversation inevitably turns to fuel economy.

Fuel economy weighs on just about anyone who drives a pickup –more so on the minds of those who have fleets of pickups to deal with and weighty fuel bills.

“I drive a 2008 GMC 2500 Sierra Crew Cab 4WD Duramax diesel everyday,” says Doug Dabney, Vice President/General Manager of Watson Construction Company Inc. based n Newberry, Florida.

“We’ve installed [torsion bar leveling] keys to the front and air bags in the rear to level it and accommodate the Nitto Trail Grappler 35/12.50R17 tires,” says the veteran heavy construction contractor who has close to a dozen diesel pickups in his fleet.

“The mpg is in the 12.7- to 13.5 range, driving normal. Our Fords get about the same. Our corporate fuel bills are huge. What modifications can I make to this truck, and to the others in my company, to increase fuel economy?”


Unfortunately, there’s no silver bullet for Dabney and the tens of thousands of contractors out there who need more ground clearance, better traction, more power or other improvements to make their trucks more efficient in the work they do.

The harsh truth is simply this: Most of the upgrades we make to our pickups hurt mpg. It’s a purely a matter of physics.

Some upgrades to make pickups more efficient on the jobsite put a hurt on fuel economy. It's a performance trade-off.

Make changes to a pickup that adds weight, increases rolling resistance, degrades aerodynamics, or causes more throttle to be used to get up to and maintain a certain speed, fuel economy takes a big hit.

For instance, you add one size taller or wider tire than came on your pickup stock.  Those four new tires are probably heavier, thus they increase rolling mass.

More rolling mass requires more energy to get to and maintain a certain speed (mass moment of inertia) . Energy is fuel. Some pickups can see a 2-3mpg drop just going up one tire size.

Now add, say, 35s and a lift or leveling kit.

Those two changes compound the hit on fuel economy because not only does the taller, heavier tires further increase rolling mass, they also create more wind resistance as your pickup motors down the road.

The taller tires also drop the overall gearing, so now it takes even more throttle to get moving—and to maintain speed.

For example, changing from 32-inch tall factory tires to 35s is the same as changing your truck’s axle gearing from 3.55s to 3.24:1.  (Original Tire Diameter / New Tire Diameter) X Original Axle Ratio = Effective Axle Ratio


Meanwhile, the lift/leveling kit adds several square feet to the frontal area of the truck. That changes aerodynamics in a negative way by increasing drag both over and under the truck. More drag, more fuel used.

Adding tool boxes and refuel tanks are a necessity for some jobs. But the added weigh cuts into fuel economy.

So that increase in ground clearance and better traction kills another couple mpg. Of course, it’s a trade-off that’s worth it if the work environment calls for such upgrades.

Add a heavy-duty bumper, big winch, toolbox and refuel tank to your work truck; all must-have tools/accessories for many in our industries. But they increase vehicle weight—and more weight takes more fuel to move. It’s physics.

Then there’s the biggest mpg killer of all: the driver. Nothing kills fuel economy faster than a heavy right foot and aggressive driving. (Well, maybe speed does, but that’s still a result of the driver’s actions.)

Engine programmers and other electronic upgrades can help mpg--if you keep the right foot off the floor.


Driving with a lighter right foot can help maximize what fuel economy might be available for the way the truck is equipped.

Accelerating lighter in traffic, easing off the throttle instead of braking at the last minute, and cruising at 65mph instead of 70mph all help improve long-term fuel numbers.

Tuners, chips, and engine programmers may improve fuel economy – but only if you control that right foot; it takes but a few seconds of heavy throttle to kill the mpg numbers you’d worked days to improve.

Other upgrades that might help boost fuel economy are those parts that improve how the engine breathes (exhaust/intake) as well as tonneau covers and bed toppers that help improve aerodynamics.

Running lighter weight oils and synthetic lubricants can also bring incremental boost in mileage. Anything you can do that puts less strain on the engine as you drive improves mpg.

When it’s all said and done, if your corporate pickup priority is maximizing fuel economy and achieving those lauded EPA numbers that were on the truck’s window sticker, then you’ll probably want to keep things stock.

That and drive like you are afraid of the gas pedal exploding if you push too hard. – Pro