The first several thousand miles on a 5.9 the mileage isn't that great.Two buddys of mine have kept 5.9s to 150k and swear that the mileage didn't get really good until 80 to 100k.

 

Your suburban gets 10mpg towing 10k lbs?

That's one sweet running chevy.

What is your mileage unloaded in your Cummins (besides "pretty much sucks")? Are you a dually with 4.10's too?

 

To the original poster I would say this: Read through all of these threads and you will see a pattern emerge. The vast majority of 6.7 owners have had few problems since the new flashes have come out, and a stock 2500 4x4 with 3.73's and an auto are getting approx 12-14 mpg around town and 17-18 mpg on the highway. Apples to apples comparisons, this is abot 2 mpg less than the average 5.9 is getting. Thats explained by the larger cubic inches and the emissions system.

There are many things that could impact someone elses mileage and make it worse than the average. They could have bigger tires (or under inflated), different gears, tool boxes or service body's that add a lot of weight or wind resistance, and/or they have a heavy foot. Or they could have something wrong wit their truck.

But, if you buy a new truck with a 6.7 in it, chances are that you will be one of the "average" owners and get the mileage I describe above. Whether you buy a 5.9 or 6.7, consider the cost of operating a HD truck like this with diesel moving towards $3.50 per gallon. Unless you really need the towing capacity of the diesel all of the time, you're probably better off getting a smaller rig with a gas engine.

 

Yes, I am amazed at how well that Sub runs and tows. I have an exhaust and intake, synthetic fluids, and that's about it. Towing my trailer it is a bit underpowered and the weight (with distribution) is killing my Autoride. If I didn't have the Autoride or some other airbag system it would definitely be a no go...

My 3500 megacab is totally stock with just over 1K miles with 3.73 gears, no dually. I've been getting about 12 to 13 around town and 15 to 16 on the highway. I got 305 miles out of my full tank of gas towing and coasted into the gas station on fumes... Overhead said 9.2

I probably would have been better off with a big block gas motor for the amount of towing I'll be doing, but thought you couldn't go wrong with the diesel which I feel good about (except for the high price of diesel which is now 3.65 a gallon and the relatively horrible towing gas mileage). I averaged between 65 and 70 max while towing. I sure hope it breaks in or someone can tweak the computer for efficiency.

 

Only 1000 miles mileage is goona suck.Could not imagine towing 10k with a gas burner again unless it was once in a blue moon.

 

I just hope it gets better from here. I'm all ready spoiled from one towing trip though and that was the main point for getting this truck!

 

I have the 6.7 in my 07 3500 6 speed and the only problem I have is not driving it long distances so the CAT fills up. I just make a high speed run to clear it out. As far as towing, I pull a 39 foot 5th wheel and the truck does great. 8 to 10 towing 15,500 lbs is not to bad in my book

 

Coming from a V10 Ram to a diesel even 12-13 mpg in town is great. I was used to 7-8. Couldn't get more than 250mi out of a tank. Now I get 400. Gotta love it.

 

If you can wait I would wait until they get this figured out, maybe the 2008 will be better. Did ford ever get there problems figured out with the 6.0

 

Whats wrong with your '99? Is it broke?
Do you owe anything on your current truck? Does your '99 do what you need it to do?

If you just have the "new truck bug", fa-ged-about-it. Save your $$$
When the economy takes a major dump next year, you'll be happy you don't have these insane monthly payments. Waiting another year or two and you'll probably be able to pick up a year old truck for $.30 on the dollar as people will gladly be able to sell their truck just to keep a roof over their heads for a few more months and food on the table.

 

whats happening to the economy next year?

 

What? You don't have your crystal ball??? Me neither.

 

LOL..........

 

With the price of fuel and the credit crunch coming down on the country like a brick wall ... it ain't gonna be pretty next year. The small business failures will accelerate quickly with people forgoing the "small things" to save $$$ for fuel and whatnot.

 

Next year, What the heck you talking about next year for.

THE ECONOMY IS TAKING A CRAP BAD NOW AND MANY SMALL BIZ ARE ALREADY BEING BANKRUPT.

ITS HERE NOW!!!! Im bout to get rid of my truck, but only for a tonka truck. Im getting out of the car biz probably and gonna start hauling big @$$ boats with my tonka truck. Nothing like making 7-8k moving a boat from florida to cali!!!