Just bought a new (used) Cap for my Supercrew, and noted some interesting MPG differences.....

I drove to NY to pick up the cap this morning. 254.7 miles. Left Mass with a full tank. Picked up the cap and re-fueled on the highway headed back, at 295.7 miles... It took 20.0 gallons, making the first leg 14.7 MPG.

Once home, I refueled again, at 509.5 miles. I took on 12.8 gallons... the second leg of the trip was 213.6 miles. This half of the trip indicates 16.7 MPG... an increase of exactly 2 MPG!

I knew that a cap would help with mileage, but never imagined it would be so great. Now I know it may have something to do with average speed (I tried to keep cruise on at 75 on the highway) and the length of time while on the highway (The longer at highway speed, the more effeceint the engine will become) but this really suprised me. Over time it will make the 385.00 investment worth while!

(It is a leer fiberglass molded cap w/ hinged side- slider front window model)

 

Are you sure you weren't driving downhill on the last leg??

 

i just lay the tailgate down... lol saved me 600 bucks for a lid

 

On this note I love to see if over the long haul makes a difference in the MPG... and how a bed cover work in the same way ...


As for the tail gate, does this work, I did this with my 2002 F150 supercrew and id not do anything over the long haul, but the tail gate was the little painful one that was not the full bed in size.

 

yeh beds on screws are short dont make much different the air moves around the cab so it doesnt hit the bed as much as in a ext cab or reg cab. but if ur cuious where ur wind resistance is drive through some smoke and see where and if u get resistance against ur tail gate...

 

I had a cap on my old truck, and it didn't make any difference. The weight of the cap itself would decrease your mileage wouldn't it? My cap on my 98 was a fiberglass with sliding window and bla bla bla but weighed around 200 lbs.