My stock 2005 2wd gets 15-17 in town putting around. On the highway theres a spot where the mpg is the best and goes down from there. 65 mph is the best speed for the best MPG. 55mph actually gets worse MPG then driving at 65.
55 gets 21mpg
65 gets 22.5mpg
70 gets 21mpg
75 gets 20mpg.

All these will go down in the winter with the winter fuel and cold engine.


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The overhead mileage is historically inaccurate - some trucks more than others. Mine reads 0.5mpg more than hand calculated. But it's very consistent.

Lots of things effect mileage, speed being #1. On the highway at 80mph, I get about 17-18. On the back roads at 55-60, I get 21-22.

Wheels and tires play a huge role here. Both weight of the wheel/tire combo, and rolling resistance are important. Heavy tires with an off road or all terrain tread will cost you miles compared to a skinnier highway tread. Match the tire to your driving, not your ego.

Most mods for mileage gains either don't work at all, or have such a minimal impact that's not worth it. For example, a big air cleaner costs $350, and gains 1mpg (if you're lucky). Do the math and see how long it will take to pay that back.

I think the only reliable cost effective mod you can do is a computer tune. Use the Smarty Jr. It's cheaper than the Sr, does a fine job on a mostly stock truck, and only takes 10 minutes to install.

Keep your tires inflated to the proper pressure for your load and tire. Over inflating will increase fuel mileage. BUT, it will also rapidly wear your tires out. Early tire replacement will easily eat up any savings from better fuel mileage - and then some.

Keep the engine warm in the winter. When it's cold (below freezing) you will see an improvement with a closed winter cover compared to an open one.

 

.boB,
What tires do you have and what mods (Smarty Jr?) have you done?

I have the Dodge aluminum rims and Michelin street tires factory size LT265/70R-17 and keep them at Max inflation. I am actually trying to wear them out as I kept a new set of tires off my GMC 1500 that are exactly the same size (and load rating E) and had less than 2,000 miles on them when I traded it (I had 2 sets of rims and tires for it). So far, I have managed 17 MPG but have to keep my speed down to 70 MPH and below to achieve that. I have kept the air filter clean and the truck is completely stock as far as I can tell - but I am the 3rd owner. Exhaust and intake look factory stock and no visable programmers. I believe the rear end ratio to be 3.73 so what do you recommend to me to get the MPGs you are? I already drive as though I have an egg between my foot and the throttle.

 

I'm using a General Grabber 245/75-17. Not my favorite tire, but I got them real cheap off CL.

My favorite tire is a Michelin LTX M/S.

The only mods I have is the Smarty Jr. Other than that, the truck is bone stock. Even the air filter box is stock. I use Cummins filters, and standard dino oil.

Oddly enough, when the air filter starts to get clogged, the mileage really drops. That happens before the filter-minder gets into the yellow zone. I try and stay on top of that.

I also have 3.73 ratio diffs, auto trans, and manual transfer case.

The only change I recommend for mileage is the Smarty Jr. There are other things you can do to pick up a few miles here and there. But they're generally not cost effective for mileage alone.

If you needed to change out the front hub bearings, then manual hubs make sense. You'll only pick up 1-2mpg. But you're replacing the bearings anyway, and with something of higher quality and easier servicability.

Same thing with the differential. If you have to rebuild it, you can got to a 3.55 gear; but you'll lose some towing ability.

Or, if you really want to spend some big bux, wait for the new 1500 with the 3.0L TD. That should get about 27-28mpg.