I can only tell you MY experience with my F-450, 4.88 gears, 6.4L, 4X4, 19.5" tires. With/without the tonneau, with/without the 5th wheel - it DOESN'T matter - 10 mpg. I just count on going somewhere and KNOWING how much fuel I will use, regardless of he setup I'm running.

 

I get MUCH better mileage with the cover. I get 18 with the cover on, between 10 and 11 when I roll it up. When I roll it up I do hook up the the 5er however.

 

Nope not a bit better mileage. It does look cool though.... funny post don.

 

I'm not completely sure on the reasoning for the people who first started this. I do know that I own a decal business and mostly to freight companies. I have to bring very big decals at times. I have a hard cover top. I feel like ive noticed a decrease in mpg but haven't been the best at tracking it. I need the hard cover to protect the decals. If they get wet from rain or too much humidity they get ruined. It would cost me lots of money. If I had to guess I wouldn't say they were for the looks. Again I'm not sure though. If your looking for aerodynamics in a truck, I really really hate to say this but ford may not be the way to go. Those goofy looking Cadillac trucks or the trucks with the Volkswagen bug looking hood are probably your best bet. Fords make a pretty strong truck and pretty good for hauling stuff. I would like to know ways to increase mpg as well. I wonder if the K&N air filters would help.

 

 

Makes no difference on my truck looks slick though.

 

ZOMBIE THREAD.

 

I don't even notice any gain. If your concern is more MPGs your better off with a tuner.

 

Look up mythbusters, they did an entire episode on this and proved it was false and did not help mpg at all

 

Best set up is take bed off.