Mine didn't seem to effect mpg's or the mds but I think they are a great addition to any truck.

 

I did not see anything with my tonneau. Mythbusters also did a test on this and found it to be no difference. Do not buy a tonneau for MPG savings.

 

Just did the trip from Florida to NC over Memorial Day. The truck is a TRX4 Crew with the 3.92 rear and Hemi. Averaged 17.4mpg up to NC and about 17.2mpg back to Florida. I was running between 70 and 75 mph in the rain going to NC and 75 back to Florida with rain the last 300 miles. Total trip was about 1,350 miles. My truck now has 13,000 miles on it (just got it the first week of January). The tonneau cover really hasn't seemed to matter for mpg, just helps keep loads dry and safe. Before the cover I did a trip to south Florida which was 335 miles round trip. Averaged 17.6 mpg on that one.

 

Saw no difference in MPG with my Bakflip.

 

My cover is to keep things dry and hidden. A bit harder to steal with the locking gate. Would have to cut it. Mine is soft... obviously.

I saw a pickup truck wind tunnel test a while back. Before mythbusters. I am old.
With the gate up the wind moved over a layer of air trapped in the bed.
Gate down and the areodynamics went way down. Far more drag.

The cover does not hurt at all but does not help much.

What rear end gear you have makes a big differnce. I have 3:92's.
3:55's do better on gas mpg. I know this from experience....and common sense.

I have XDI intake, bed cover and mufflex 24".
I see high 17's to mid 18's hwy. Stop and go city. 16.+

 

According to Bountyhunter his gave him an extra 25hp and increased his quarter mile time by over a second!!! I bet you can really increase your gas milage and performance by using one of these!!!

 

I haven't seen any significant savings with the tonneau maybe .5 mpg but do like it when windier seems to help with the cross winds not pushing the truck around as much. As stated I would struggle to pencil it out for MPG savings but they are real nice to have. I got the Mopar Tri-Fold and it is easy to install/remove by myself and leaves no mounting hardware when removed a slick setup in my opinion.

 

It won't help MPGs. Just hopefully keep your gear safe & dry (depends on model of course).

According to mythbusters and others, it doesn't help MPGs. Neither does lowering your tailgate. That is actually worse. And removing your tailgate is negligible.

 

from what i remember they said air "fills" up the bed while driving and its actually pretty aerodynamic.lol...

yeah. ive got the extang solid fold on my truck. its BAD ***!!

 

cicdude and nchockey said everything i would have said.

i didnt notice any gains in my mpg but yes the look, added security and ease of removal earns my bakflip a good buy award