Hi matth_chevy,

Welcome to the Chevy Forums.

The two biggest mileage improvers for my truck were a gear change(3MPG), and an aerodynamic fiberglass cap. (3MPG)

HOWEVER, I'm going to keep my truck forever(knock wood), so these VERY
costly mods will not only pay for themselves, but also provide a major payback in fuel economy.

The gears, 342s, are very doggy in the low end, but provide very low rpms in the highway range, down @1200 RPM in general from 410s. COST: 2000$$ OTD. I've also doubled my city driving MPG with this mod, and very sedate driving.

The Fiberglass cap(appearance is a personal preference, as is weight, so it would be almost useless to start in about name brands) will limit your carrying ability in your bed somewhat, for larger loads. Tonneau covers work very well, also. COST(for mine) 1400$$ OTD

But due to overall expense, and how long you may be keeping your truck, and what kind of driving you do, these expensive changes are definitely not for everybody.

 

Therewolf, did you really get 3 mpg from the bed cover?

 

Hey, nobody was more surprised than me.

I just wanted it because I do a lot of camping. The fuel savings was unplanned.

Funny thing is, driving away from the dealer where I got it, for a little while I thought I was actually getting worse mileage. Then I got a full tank and did the math.

I've got a 2500HD CCLB 4X4with a 6.0 L and a 4L80E. Your mileage improvement may be more or less than mine.

 

Ahhh I see. Yeah I only have the 5.3 and 4L60e, so I probably would not see as much improvements in mileage... But I do have the 3.43 gears

I am wanting a hard cover, but I also want a stepside bed... soooo kinda wanting to hold off on a cover until I actually get the bed I want, ya dig? Plus I am thinking just the stepside bed would get me better mileage since I have heard they are made of lighter materials and maybe a little more aerodynamic? Who knows.

 

Yeah, you have to go with what works with you.

My costs, for instance would be practically silly for anyone not planning on keeping their truck for the long haul.(no pun intended)