Quick camper shell question?

[FunkBlastin]

I was able to find a gently used fiberglass camper shell for my 1991 3.0L.
In anyone's experiance, how will this effect my MPG? Good? Bad? Discuss.

 

[gcfishguy]

Actual camper, or just a cap?

Bought a cap (not a camper) a couple weeks ago for mine (2008 3.0 5-spd 4:10's) and the highway mileage went up by 2mpg.

Lots of people say it will raise the mileage, but I read some controlled tests that say it lowers mileage.

I'm sure there's lots of opinions but I've been tracking my mileage since i got the ranger, and like i say, highway mileage is up by 2mpg.

 

[FunkBlastin]

Yah, just a cap. I was thinking it would raise it a little. My truck seems to drive a little better on the highway too.
Thanks!