Guides
Do Tonneau Covers Improve Gas Mileage?
Three published tests, three different answers, and one of them is negative. Here they all are rather than the one that flatters the category.
By Michael W. · Published October 5, 2026
Cover & Cargo earns a commission from qualifying purchases made through links on this page, at no extra cost to you. It does not change what we recommend or the order we rank things in — here is how we choose and here is the full disclosure.
What this is based on: published manufacturer specifications and warranty terms, cited on each cover; independent published tests where they exist, named and linked; and verifiable owner reports of specific failure modes. We have not fitted these covers to a truck, we do not run a test lab, and we do not claim a test we did not run. Where the evidence for a cover is thin, the page says it is thin.
Quick picks
| # | Cover | Best for | Score | Price |
|---|---|---|---|---|
| 1 |  BAKFlip MX4The default hard folding cover, and the one most buyers should start from: 400 lb rating, a 5-year warranty, 100 percent bed access, and a seal design the maker revised specifically to stop bulkhead seepage. | Lowest-drag type | 8.4out of 10 | |
| 2 |  TruXedo TruXportThe roll-up most people mean when they say roll-up: vinyl over a clamp-on frame, 30 minutes to fit, 5-year warranty, rolls forward for 100 percent bed access with nothing left in the bed. | Vinyl roll-up | 7.6out of 10 | |
| 3 |  RetraxPRO MXThe manual version of the same idea and, for most people, the better buy: 500 lb rating, a limited lifetime warranty, double-wall aluminum slats, and no motor to fail. | Flush retractable | 8.4out of 10 |
Scores are our own editorial judgment on the rubric published at our editorial policy page, weighing security, weather sealing, bed access, install effort, durability, value. They are read off published specifications, warranty terms and sourced owner reports. They are not measurements we took, and they are not user ratings.
The short answer
The published tests do not agree, and that is the answer. One wind-tunnel study found just under an estimated 2 percent fuel improvement. One road test found 7.7 percent. One found a 4 percent loss.
The drag reduction is real and small. What it does to your fuel consumption depends on your truck, your speed and your driving.
Do not buy a cover for fuel economy. Buy it for weather, privacy and security, and treat any economy gain as a bonus you might not get.
The three published tests, side by side
This is the table nobody else publishes, because each of these results on its own supports a different conclusion. Together they support the honest one.
| Test | Method | Result |
|---|---|---|
| SEMA wind-tunnel study (researcher Megan McKernan) | 13 tonneau cover types, wind tunnel | About 5 percent reduction in drag, for just under an estimated 2 percent improvement in fuel efficiency. Best performers were fiberglass and roll-up vinyl, topping out above 6.5 percent drag improvement |
| The Fast Lane Truck road test (2022) | 2022 Ram 1500 Classic, 57 miles, with and without a cover | 19.533 mpg without, 21.142 mpg with. A 1.61 mpg gain, 7.7 percent |
| Consumer Reports road test | Dodge Ram V8 at 65 mph | 22.3 mpg baseline, 21.4 mpg with a soft cover. A 4 percent loss |
| MythBusters (episodes 43 and 64) | Truck aerodynamic modifications | No significant change in efficiency with a hard cover; a mesh tailgate improved mpg most at about 5 percent; driving with the tailgate down was least efficient |
Each result is reported as published by the source named. We did not run any of these tests and we have not independently verified them - the links in the Sources section are where each figure comes from.
Why they disagree
Not because any of them is wrong. Because fuel economy is sensitive to a great many things that differ between tests.
- Speed. Aerodynamic drag rises steeply with speed — one report notes drag increasing by as much as 75 percent going from 45 mph to 60 mph. A test at 65 mph and a test at 55 mph are measuring different things.
- Truck shape. The airflow behind a cab differs between trucks, and what a cover does to it differs with it.
- Cover type. The wind-tunnel study found fiberglass and roll-up vinyl covers best, above 6.5 percent drag improvement, while others in the same 13-cover set did much less.
- Measurement noise. A 57-mile road test has real-world variance that a wind tunnel does not.
A Motor Trend test from 2007 reported a 1.3 mpg improvement on a Hemi-powered Dodge and 0.5 mpg on a Chevy, with a Ford removed from the test after trouble. Same conclusion: it varies by truck.
The mechanism is real
An open truck bed is a cavity. Air gathers behind the cab, swirls, and leaves at the tailgate in a way that costs energy. Ford's design manager Brad Richards confirmed in 2014 testing that covers reduce drag by keeping air from gathering in the back of the cargo box.
So covers do reduce drag. The disagreement is entirely about how much of that reaches your fuel bill, and the answer appears to be: a little, sometimes, depending on circumstances nobody can predict for your truck.
Why we are not giving you a number
Because there is not one. Any site quoting a single percentage has picked one of the results above and ignored the others. The figure that is most defensible from this evidence is “under 2 percent at best, and possibly negative”, which is not a number that sells covers.
If you still care about the aerodynamics
The wind-tunnel study found fiberglass and roll-up vinyl covers performed best of the 13 types tested. That points toward a flush-fitting hard cover or a tensioned vinyl roll-up rather than a tall, stepped folding stack, and toward keeping the cover closed on the highway rather than folded open.
Two other things are better supported by this evidence than the cover itself: MythBusters found a mesh tailgate improved mpg most at about 5 percent, and found driving with the tailgate down was the least efficient option of those tested. Closing your tailgate is free.
The picks in detail
#1 · Most truck owners
BAKFlip MX4
BAK Industries · Hard folding
The default hard folding cover, and the one most buyers should start from: 400 lb rating, a 5-year warranty, 100 percent bed access, and a seal design the maker revised specifically to stop bulkhead seepage.
What it does well
- 400 lb evenly distributed rating is at the top of the folding class, and it is published rather than implied
- The revised EPDM perimeter seal plus drain system targets the bulkhead, which is where folding covers actually leak
- Folds flat against the cab for full bed access without taking the cover off the truck
- 5-year warranty is longer than most hard folding covers in the same bracket
Where it gives way
- Folded open it occupies roughly the front third of the bed — the published 100 percent access means the bed is reachable, not that the space is free
- Textured black finish shows water spotting on dark trucks more than a gloss panel does
- No published figure for cover weight, so the one-person-install question is unanswered by the maker
Skip it if: Anyone who needs the bed open and covered at the same time all day. Folded against the cab it eats the front third of the bed, and nothing folding escapes that.
| Construction | Multi-layer aluminum, polymer-reinforced top panels |
|---|---|
| Finish | Textured matte black |
| Load rating | 400 lb, evenly distributed |
| Warranty | 5 years |
| Stated install time | 30 minutes or less |
| Drilling | None required on most trucks |
| Bed access | 100 percent — folds flush against the cab |
| Sealing | EPDM perimeter seals, integrated drainage |
Specifications read from RealTruck — BAKFlip MX4 (Gen 3) published specifications.
#ad We show no price until we can verify one. How this is funded
#2 · Full bed access on a budget
TruXedo TruXport
TruXedo · Roll-up (soft)
The roll-up most people mean when they say roll-up: vinyl over a clamp-on frame, 30 minutes to fit, 5-year warranty, rolls forward for 100 percent bed access with nothing left in the bed.
What it does well
- Rolls completely forward, so full bed access costs you nothing but the roll itself
- 5-year warranty on a soft cover at this price is genuinely good
- Lightest install in the registry — 30 minutes, no tools beyond what is in the box
Where it gives way
- Vinyl offers no meaningful theft resistance; treat it as a weather and privacy cover
- Rolled to the bulkhead it sits proud of the rails, so it is visible and in the way of a full-height load
- Vinyl needs a UV protectant on a schedule or it chalks
Skip it if: Security. A soft vinyl cover keeps weather and eyes off your cargo; it does not stop a knife.
| Construction | Vinyl over a clamp-on aluminum frame |
|---|---|
| Finish | Vinyl grain |
| Warranty | 5 years |
| Stated install time | 30 minutes or less |
| Drilling | None — no cutting, drilling or modifications |
| Bed access | 100 percent — rolls forward to the cab |
| Mounting | Clamp-on, vehicle-specific hardware included |
Specifications read from RealTruck — TruXedo TruXport (Gen 2) published specifications.
#ad We show no price until we can verify one. How this is funded
#3 · A retractable that will outlast the truck
RetraxPRO MX
RETRAX · Retractable (manual)
The manual version of the same idea and, for most people, the better buy: 500 lb rating, a limited lifetime warranty, double-wall aluminum slats, and no motor to fail.
What it does well
- Limited lifetime warranty on a 500 lb retractable is the strongest published pairing in this registry
- Locks at any point along the bed, not just closed — genuinely useful with long cargo
- Operates independently of the tailgate, so the tailgate is not part of the security story
Where it gives way
- The canister still costs you bed length at the bulkhead, same as any retractable
- Warranty does not transfer to the next owner
- Costs more than most folding covers that carry a lower, but adequate, rating
Skip it if: A second owner — RETRAX publishes the lifetime coverage as non-transferable.
| Construction | Double-wall aluminum slats |
|---|---|
| Finish | Matte black powder coat |
| Load rating | 500 lb, evenly distributed |
| Warranty | Limited lifetime, non-transferable |
| Locking | Key-lockable TraxLatch handle, infinite locking positions |
| Stated install time | Less than 60 minutes |
| Drilling | None — clamp-on rails, four quick-attach clamps |
| Temperature tested | -40°F to 180°F |
| Sealing | Integrated water management with drain tubes |
| Origin | Assembled in Grand Forks, North Dakota |
Specifications read from RealTruck — RetraxPRO MX published specifications.
#ad We show no price until we can verify one. How this is funded
Common questions
Do tonneau covers improve gas mileage?
The published tests disagree. A SEMA wind-tunnel study of 13 cover types found about 5 percent less drag for just under an estimated 2 percent fuel improvement. The Fast Lane Truck measured 19.533 mpg without a cover against 21.142 with one over 57 miles — a 7.7 percent gain. A Consumer Reports road test on a Dodge Ram V8 at 65 mph measured 22.3 mpg against 21.4, a 4 percent loss.
How much mpg does a tonneau cover add?
There is no single defensible number. The most honest reading of the published evidence is 'under 2 percent at best, and possibly negative, depending on your truck, speed and cover type'. Any site quoting one percentage has picked a favorable result and ignored the others.
Which type of tonneau cover is most aerodynamic?
The SEMA wind-tunnel study of 13 cover types found fiberglass and roll-up vinyl covers performed best, topping out above 6.5 percent drag improvement. That points toward a flush-fitting hard cover or a tensioned vinyl roll-up rather than a tall folding stack.
Does driving with the tailgate down save fuel?
No — MythBusters tested it and found driving with the tailgate down was the least efficient of the configurations they tried. A mesh tailgate improved mpg most at about 5 percent. Closing your tailgate costs nothing and is better supported by the evidence than the cover is.
Sources
- SlashGear — reporting the SEMA wind-tunnel study of 13 tonneau cover types
- The Fast Lane Truck — 57-mile MPG road test with and without a tonneau cover
- AmericanTrucks — collected fuel economy test results including the Consumer Reports road test
- RealTruck — BAKFlip MX4 (Gen 3) published specifications, read 2026-10-05
Read next
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