Everyone I know has said it's one or the other: gas mileage or power. I would like to know how you get both, because I don't think it's possible. Maybe by using a $4,500 supercharger, but I don't know anyone who has one to verify that.

 

Have a 02 Screw 5.4l. I recently went from stock wheels and tires which i was getting around 15 avg for city/hghwy. I put on 33s with 18" wheels and lost about 2 miles per gallon. I have a cai and duals. Also have checked gas mileage with my hard cover and a soft cover and there was very little change. Maybe a half mile per gallon.

 

Popsci, might have been popmec just talked about this.
Leaving the tailgate up, helps. But only a little.

 

My 4.6 scab 4x4 gets about 20mpg on the highway. I went from Lima, OH to Cleveland, OH on a 1/4 tank of fuel. That was with cruise and a/c running. Talk about surprised! I know some of it will go bye bye when the tires go on, but once it's geared I hope it returns...