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Fuel Economy of Tonneau Covers Questioned

September 18, 2007 by Simon

You may have heard that you can improve the mpg of your truck by covering the truck bed with a tonneau cover.

I just read that SEMA has done some research on the effect of truck bed covers on the aerodynamics and it seems they found out that covering the bed on your truck will reduce drag by 4.2%–7.8%, effectively reducing the amount of fuel you have to use to overcome air resistance.

I read a post about this research over at Thundra Headquarters where the admin thinks the fuel savings are too small to warrant the considerable cost of buying a new tonno. Instinctively I don’t agree as there is other uses for a bed cover than just to save fuel

I was also qurious if the calculations are true, so I did some of my own. The main thing to consider here is that the tonno only improves the aerodynamics to a noticeable degree when you drive at highway speed. And not all of the fuel is used to push air, some is also used to overcome rolling resistance.

I will calculate with a 3% fuel saving on a 20mpg truck, doing a 20mile highway commute every day making it a total of 50miles per day with off work driving. I will also use a 6 day week to account for other than commute driving.

20mpg is 0.05 gallons per mile. 3% of this is 0.0015 gallons saved for every mile you drive. The total miles in a year is 50 miles x 6 days x 50 weeks in a year. This makes for 15000 miles a year with 0.0015 gallons of gas saved for every mile, thus 22.5 gallons saved.

With a gas price of $3 per gallon this would make a total saving of $67.5 per year with the tonno cover comared to driving without one, not bad.

Lets say you own you tonneau for 5 years, you will save $337.5 over this period.

What can I say, you won’t be able to pay for more than the most basic truck bed cover with the gas saved, but then again don’t you wan’t to have a cover?

There’s so many other reasons to get a tonneau cover for your truck than just to save gas. It will keep your stuff dry when driving in the rain, it will keep your stuff clean when driving in the dust. It will keep you light stuff from flying away when you drive on the highway.

It will also prevent you stuff from walking away when you stop in the city and if you get one that you can lock it will also prevent you stuff from walking away at night, when parked in the open.

With all these reasons to get a cover, isn’t it great that the gas savings of the tonno itself will pay for most of it?

Just remember that you get the most savings if you drive highway miles, if you are only driving around town doing street speed you won’t save much.

If when reading this you feel like you got a good reason to go get a new tonneau cover for your pickup truck, I have listed some reasonably priced tonnos from a US dealer here:

How to Save Gas With A Tonneau Truckbed Cover  

And always remember, if you need to check your gas mileage the mpg calculator is over at the main page.