Tonneau covers may improve gas mileage slightly by reducing the drag coefficient (basically making your truck more efficient), but tests have shown there are other factors at play that can offset that efficiency. But what does that mean for your wallet?
Bottom line: a tonneau could save you up to around $53/year on average.*
While that means a tonneau cover could potentially pay for itself eventually, it's worth noting that's probably a best-case scenario, as there are a lot of factors at play that we'll dive into in detail below.
In the meantime, here's what three of the most reliable tests found about how bed covers affect mpg.
MythBusters Tonneau Cover Gas Mileage Test
The popular show “MythBusters” dedicated two episodes to testing gas mileage for pickup trucks. In an episode 43 segment titled "Tailgate Up or Down" the crew found that it's less fuel-efficient to drive with your tailgate down.
However, fans kept writing in about other pickup truck aerodynamics hacks, like adding a bed cover, using a mesh tailgate alternative, and removing the tailgate altogether. “MythBusters” revisited the topic in episode 64 to test them and found:
- The mesh tailgate improved mpg the most (+5%)
- No tailgate, tailgate up, and hardcover were fairly equal
- Driving with the tailgate down was the least efficient
Granted, this was one truck on an open road with one type of hardcover, so there's some wiggle room for the data to vary for your setup.
Results: No significant change in efficiency
Specialty Equipment Market Association Study
The 2007 study by Megan McKernan, research and information specialist for the Specialty Equipment Market Association (SEMA), is easily the most comprehensive study on record.
McKernan tested 13 types of tonneau covers in a wind tunnel, and reported they led to a 5% reduction in drag for just under an estimated 2% improvement in fuel efficiency. The best performers were fiberglass and roll-up vinyl options, topping out with over 6.5% drag improvement.
Before you take those numbers as gospel, there are a few things worth noting here:
- McKernan notes some of the best findings were specifically for a GMC Sierra, and it's likely other models could see different results.
- The efficiency improvement is an EPA estimation based on an average speed of 48 mph.
- Adding weight to the truck with heavier covers could offset any gains in aerodynamics.
- Testing was done in a controlled environment, so real-world performance could vary.
- SEMA as an organization operates on behalf of the specialty equipment market.
Results: Estimated 1.8% improvement in mpg for some tonneau covers>
Consumer Reports Findings
In 2013, Consumer Reports also ran a study on how tailgates and tonneau covers affect fuel economy. While the organization is probably the most impartial and reputable of the three, their study was also the most limited.
This road test on a Dodge Ram V8 showed that at 65 mph, using a tonneau cover or leaving the tailgate down would actually decrease fuel efficiency slightly. The dip for the tonneau cover was pretty minor, going from 22.3 mpg to 21.4. But like the other studies, there are a few key notes to think about:
- This test was done with one truck on the same road, so performance could vary by model, conditions, and location.
- The experiment only tested for driving 65 mph.
- Only a "factory soft tonneau cover" was tested, and the SEMA study showed other cover types performed better in terms of fuel economy.
Results: 4% reduction in mpg for soft tonneau covers
How Do Tonneau Covers Affect Truck MPG?
Generally speaking, tonneau covers can reduce drag—but the same isn't always true about fuel consumption. There's no simple answer to the question of whether tonneau covers improve gas mileage because there are a handful of factors that affect the equation.
Pickup Truck Aerodynamics and Drag
The theory behind the tonneau cover gas mileage equation is pretty simple—you're probably already picturing them stopping wind from getting caught up in your tailgate. Tonneau covers do improve aerodynamics to some extent, cutting down on drag.
That's why they improved fuel efficiency in some of the test scenarios above. It's also why removing the tailgate and replacing it with mesh also helped.
Bed Size and Tonneau Cover Weight
Here's MPG 101: The heavier your truck, the harder your engine works; the harder your engine works, the worse your fuel efficiency. In fact, the U.S. Department of Energy (USDE) claims that every additional 100 pounds of weight can translate to a 1% drop in fuel efficiency.
If you opt for a long box, for example, you increase the overall weight of your truck. Cap that bigger bed with a long, heavy tonneau cover on top, an—in comparison to a short bed with no cover—you could be adding a few hundred pounds to tow around even with your bed empty.<
Driving Speed and Acceleration
Acceleration and higher driving speeds also translate to lower fuel efficiency: The USDE notes that the threshold varies by vehicle, but generally, it drops significantly the faster you go above 50 mph.
However, the SEMA study above found that drag improvements from tonneau covers generally increased as driving speed went up. Not enough of an increase to offset the efficiency you can gain by driving the speed limit, but still helpful.
Truck Age, Condition, and Maintenance
At the end of the day, all these factors still can't account for one wild card: the condition of your specific truck. A brand-new ride with top-shelf fluids and perfectly inflated tires will get better mileage than a comparable one that's a decade old with balding tires and a shaky oil change history.
Other Benefits of Tonneau Covers
Let's say you drive an electric F-150 and aren't that concerned about saving gas—tonneau covers still bring a bedload of other benefits like security and storage.
- Organization: Turn your bed into an enclosed storage compartment for your tools, gear, and accessories.
- Storage protection: Keep the rain, sleet, snow, and dust off your stuff.
- Bed protection: Maintain your bed and liner by blocking out the elements.
- Security: Lock your cover up to keep your valuables safe while you're on the road.
- Appearance: Give your bed a sleek, finished look with a cover designed to match your model and paint color.
- Resale value: When it comes time to resell, a quality tonneau cover will make your truck more attractive to potential buyers.
How To Get Better Gas Mileage in a Truck
Tonneau covers may be able to bump your gas mileage up a bit in some circumstances, but if you really want to take your efficiency to the next level, consider some of these gas-saving tips.
- Ensure fitment: If you decide to use one, make sure your tonneau cover fits properly by measuring your truck bed first.
- Slow down: No surprise here—Consumer Reports considers this the best way to save fuel, calculating that you can save as much as 7 mpg by going 65 instead of 75.
- Accelerate/brake wisely: Accelerating and hard braking are mpg killers. Pay attention to your surroundings so you can speed up and slow down gradually.
- Use cruise control: If you've got a lead foot, cruise control can keep you from speeding and hitting the brakes.
- Cut the extra weight: Lighten the load on your engine by lightening the load in your bed. If you're towing around heavy tools and accessories you don't need, move them to the shed for an instant mpg boost.
- Maintain tire pressure: According to a USDE report, you can boost your efficiency by up to 3% by maintaining proper tire pressure.
- Mind your manual: Always abide by factory recommendations when it comes to oil type and other maintenance components. Going off the book could hurt your truck's performance.
- Keep up with maintenance: A healthy truck is an efficient truck. Don't get lax on your maintenance schedule if you want maximum fuel economy.
Final Verdict: Do Tonneau Covers Save Gas?
At the end of the day, do tonneau covers save gas? Based on independent studies from “MythBusters,” SEMA, and Consumer Reports, yes—in some cases.
Here's a summary of the research findings:
- At best, tonneau covers improve gas mileage by under 2%
- Gas-saving benefits increase at higher driving speeds
- The best-performing tonneau cover types are fiberglass and vinyl
- Heavier options may offset any gains in fuel efficiency
If you're purely looking for gas savings, tonneau covers might be able to help a bit. But there are plenty of other reasons to install one, and plenty more tactics for improving your mileage. You can't go wrong by adding a cover or other bed accessories to your truck.
*Cost calculation of $52.87 was calculated based on Federal Highway Administration estimates for average miles driven per year, AAA estimates for the national average cost of gasoline per gallon, and FuelEconomy.gov estimates for the average mpg of the F-150 with a base 3.3-liter V6 engine.
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