I don't care what the Mythbusters proved....I saw that show.....but I recently received a tri-fold tonneau cover from my oldest son that he got in a deal helping someone move and installed it on my F-150, 4.6 auto.
My "average" mileage went from 17 to 19 mpg. That is no lie! On the highway, mileage went from 21 to 23.
It's held on with 4 toggle clamps and comes off easily if I need to haul anything.
I also don't drive with a "heavy" foot either.

 

Id like to get something close to what you were before the improvement.

 

I work at ShurCo the manufacturer of the Truxedo Lo Profile and we have done our own studies on tonneau covers in regards to gas savings. We found that you can increase your savings by 1 or 2 mpg. Also, this comment appeared in Tailgate Talk by Bruce Smith who is quoting a Ford engineer.:

According to many of those same experts, the best way to improve a pickup's fuel economy is to leave the tailgate up and cover the bed with a quality after market tonneau cover."Tonneau covers on pickup boxes reduce aerodynamic drag" said Ford's Jack Williams. "we've seen reductions of about 8 to 10 percent on the F150, which means the average fuel economy improvements for the EPA city/highway cycle(test) is about 2 percent."The average steady-state (cruise control) fuel economy improvement at highway speeds is close to 5 percent.."Adding a tonneau could mean an improvement in fuel mileage that is the equivalent of a free gallon of gas for every 20 gallons used.

 

Like I said Homer, I don't drive with a heavy foot because of the fact that if I pushed the truck, my mileage would go down. I know this for a fact. Plus, pulling a 16 foot trailer with 2 full size atvs and 1 youth atv with the overdrive out will cause my mileage to drop.

 

Im 50 yrs old, and I dont drive like a teenager either..

 

The myth doesn't hold true for any truck, my '82 never showed any change with or without a tailgate, but any type of bed cover will improve mileage some.

As you both have stated without actually saying it, the ultimate mileage improver is your right foot.

-Kerry

 

Can't argue with Mythbusters.