18 mpg

[tempforce]

i just ordered air tabs to install at the rear of my bed cover. we'll see if they help the mileage any.

if they do, i'll install them on both of my trailers.

they are supposed to break up the air drag at highway speeds.



it seems that 2x4's get 2-4 mpg better mileage. but it could be the way i drive as well.

 

[Adventure Bob]

Just ran from Ft Walton Beach Fl to Atlanta GA at 19. 4 at an avg of 71MPH. Truck was empty. I put a cool blue hose and the AFE filter in about 3 weeks before this trip and around town Im getting right at 22MPG. Once on the highway, a brick is a brick and aerodynamics are against us.

 

[dmclean]

08 manual reg cab long bed 4000 miles about 13 mpg unloaded-overhead says 15. 5-16-this mileage sucks

 

[pcarlson]

Just drove from Wisconsin to Alabama and hand calculated at 18. 2 mpg. Not bad for not even 3000 miles on the ticker. Drove 68-70 mph empty.

 

[AHarris]

08 manual reg cab long bed 4000 miles about 13 mpg unloaded-overhead says 15. 5-16-this mileage sucks

Try a bedcover. Makes a huge difference.

 

[Trashdawg]

07. 5 3500 mega, 25k miles, no eng. light no problems. It gets 17 hand calc freeway.

 

[AHarris]

Mileage

17-18 on the highway, 15-16 around town. 2007 1/2 3500 QC 4 X 4 with 6. 7, latest flashes, G56 and 3. 73 gears. Not bad for a 7500 pound truck.

Haven't noticed a difference between diesel bought in Texas and my last fill up in San Jose California.

 

[SNGLESHOT]

Happy with my 08 MPG!

Getting good mileage from my new 08. only 15K miles, all stock. Drove from Sierra Vista to Tucson AZ; around 60 miles, experimented with lower speeds and got 26 MPG!
Cruise control set at 60 mph and speed limit is 75 on I-10.
Drove from Sierra Vista AZ to Salt Lake UT 975 miles one way. Stayed five days there, heavy snow used 4WD, lots of mountain canyon driving in Wasatch Mtn range, hauling 5 people. Total trip avg equaled 20. 8 mpg doing max speed limits when possible! Am I happy with this truck? H*LL YES! I do have a bed cover, 373 rear gears and 6 spd auto. Like I said truck is all stock. Avg around 17-18 city. Not bad for a truck weighing over 7,000 lbs.

 

[AHarris]

I didn't mention that I'm getting this mileage running at freeway speeds. For this truck, the sweet spot seems to be at 77 mph indicated on the Tom Tom GPS and running around 2350 rpms. She just seems to purr along. If I run at 70 or go up to 80, I'm down to 16. 5. It's hard to imagine that this big 409 cubic inch motor seems to enjoy higher RPMs in the low 2000s. But get too much above 80 and the engine seems to be spinning faster than it likes to.

This brings me to a question about the 6. 7 that you guys might know: how much RPM is too much over the long haul? If I was out on a lonely interstate running 80-85 and turning 2500+ is that bad for the engine? Not that I want to do that too often, but it's good to know where the limits are.

For towing, the sweet spot runs around 65 with about 14 mpg. But I'm only pulling a 25' camper that weighs around 4,600 pounds so the truck is not working hard at all.

I am using a bed cover also.