Does A Camper Shell Boost Gas Mileage?

Pickup trucks are prized for their high amount of torque, towing capacity, and payload. However, one area in which many of these vehicles don't excel is fuel economy. However, diesel trucks can get some fantastic miles per gallon, given some of their advantages over gasoline. And this is the diesel engine truck that gets the best MPG in 2025. But what happens to fuel economy when you add a camper shell over the bed? Does the enhanced aerodynamic quality of the shell improve things, or does the weight increase of the add-on reduce fuel efficiency? It turns out, both end up being true. YouTube channel The Fast Lane Truck investigated this very question, measuring fuel economy with and without a topper, logging 18.16 miles per gallon without and 18.26 miles per gallon with a camper shell.

In truth, weight has a significant effect on how thirsty an engine is, with the U.S. Department of Energy explaining that adding 100 pounds to a vehicle can result in a fuel economy loss of up to 2 percent. A full bed CX Series truck cap from A.R.E. weighs in at 185 pounds, which is certainly not helpful in conserving fuel.

Speaking with Edmunds, Max Schenkel, General Motors technical fellow, explained, "For a full-size truck, a change in drag coefficient of 0.01 is approximately equal to an improvement in fuel economy of 0.1 mpg." Suffice it to say, any reduced drag provided by the shell that enhances miles per gallon is subsequently canceled out by its weight.

While a topper or camper shell might not provide much in the realm of improving miles per gallon, surely a tonneau cover might prove useful? A tonneau cover is basically a lid for a truck bed, securing cargo safely inside. There are several variations of these products from folding, rolling and retracting designs, to solid one-piece units. But, when compared side-by-side with an open bed, does the cover provide better fuel economy?

Yes, a tonneau cover does provide trucks with more miles per gallon. Motor Trend conducted some testing at a southern California speedway with a variety of pickups, both with an open bed and utilizing a SnugLid tonneau cover and found an improvement of between 4-and 10 percent fuel economy. Of course, there are several variables involved, so results will highly depend on the truck, the engine, and even the weather during testing. However, if you're looking to squeeze a few more miles out of your tank, adding a tonneau cover will help (and you should choose one from the highest-rated truck bed cover brands).

There is another common misconception in terms of improving truck fuel economy, and it has to do with the tailgate. Specifically, that you should drive around with your tailgate down, which presumably would allow the air to flow over the cab and down through the bed unimpeded. And while that sounds plausible, when you lay your tailgate down, you're instead increasing the drag, and thereby negatively impacting miles per gallon.

When the tailgate is up, a circular pattern of air develops in the truck bed as you drive. When the oncoming air flows over the cab, it continues right over the rotating section of air in the bed, reducing drag. When you drop the tailgate and drive, you end up creating a section of turbulent air behind the cab, and it builds up in the back of the truck, reducing aerodynamics. Driving with your tailgate down isn't the only misguided theory floating around, as there are several MPG myths that aren't actually helping you get better mileage.