Anyone with a tonneau cover, did your mpg increase and by how much?

 

I watched a TV show called "Mythbusters" and they did some experements. This is what I remember:
Topper/Tonneau cover/open bed with tail gate up....Pretty much the same wind resistance. Not a noticable mileage difference.
Open bed with the tailgate down...More wind resistance and lowered the MPG.
The reason the open bed with tail gate down was worse than the others is because the wind resistance pulls on the outside and inside of the bed. If you have the tailgate up, there is an "air bubble" that does not have as much resistance on the passing air as the inside of the truck. You can witness the air bubble in the back if you have loose leaves or something back there. The leaves usually swirl around, but don't take off right away. I had a pop can float in the back of my truck for a good 20 seconds once at about 55 MPH.

 

made no difference to my mpg

 

which cover do you have?

 

I had a hard cover on mine. It was called tri glass I think. According to my overhead I am getting about .7 less right now than I did with the cover. But honestly I think its just the way I've been driving. lol those mustang cobras are fun as hell to mess with on the road

 

yup mythbusters busted that one, i have it tevoed if you wanna come and watch it.

 

haha, i can stand that show, lol

 

has anyone used or have a retractable cover they liked? i've seen a few, and not sure how secure they are, even with a locking tailgate

 

I don't care what mythbuster said. Driving on the high way (for a few hours) it definitely increased my mpg. Not by much though.

 

what cover do you have?