Based on the video and the comment about high pressure buildup in the bed I would say that a tonneau cover will do little to nothing for increased mpg and actually may hurt your mpg but without further testing this is just an assumption.

 

I cant remember where I saw it but they did a study with actual 09 F150s in 5.5, 6.5, 8ft beds and they found that the tonneau covers did reduce drag but it was SOOOOOOOO little that it did nothing for MPGs. https://www.f150forum.com/f2/tonneau...mileage-20851/ this has some of the links some have been removed. interesting about the 8 ft bed........ interesting, makes sense.

 

I don't like the look of that little flap thingy down there, but I'm leaving it in place until I lower the truck with the help of a GroundForce kit

 

there was an episode on mythbusters about the tailgates. the truck with the tailgate up got better mpg and i believe it was noticable by a few laps around the track they used. i imagine the cover will help, however minimally unless you drive with the tailgate down with the cover off

 

I took my flap-thing off at the first oil change. Makes is a hell of easier to access the front of the engine. Plus, the way I use my truck, it will probably get ripped off anyway.

-although, it is a pretty rugged little piece.

 

^ x2 i've had it off for a while and have not noticed any difference other than it doesnt drag the ground anymore..

 

I am not concerned as much as the "air-effeciency" that it provides as much as I am as that it may provide some sort of up draft wind to cool the e-fan... don't want the truck to over-heat.

Have you noticed the truck running warmer?

Thanks,
Jon

 

Nope.

However, I took mine off at 1100 miles and to be honest, I haven't really been paying close attention to operating temp. I figured the thing was for mpg's and I was not aware of the 09/10 e-fan difference.