6.7 milage

[JBixby]

I just sold my 2006 5. 9 turbo and bought the new 3500 hoping it will last longer than I will. The truck may last that long but the mileage I am getting is a concern. I only have 1500 miles on the truck so it is not completely broken in but I am only averaging about 14-15 MPG. Does any other out there with new 6. 7 have any comparative mileage? I was getting 19=21 with the 5. 9 sure hoping I didn't make a mistake.

 

[LBARTLETT]

if your only consideration is mileage than yes, you made a mistake



there are mods that can be done for mileage improvements but they will all void your warranty

 

[AHarris]

During the first 30K miles on my truck I was averaging around 15. City mileage was around 13 and highway was 14-16. Now I'm getting about 17-18 at 49K miles. However, where I live it's all highway driving. I have 3. 73 gears.

IMHO, pretty damn good numbers for a 7500 pound vehicle with a 409 cubic inch engine.

 

[LBARTLETT]

I have no problem with the mileage my trucks get, they are huge trucks able to pull anything I want to hook to them



the stock 6. 7's just don't seem to get the overall mileage the 5. 9's did



I just did the deletes on the megacab at 108k miles, made 2 mpg difference

 

[mpaulson]

I did all the deletes back about 170,000kms ago and it made absolutly no difference in my fuel mileage. Had I known, I wouldn't have voided my warranty so soon.

 

[LBARTLETT]

mpaulson, I should clarify some, our megacab dually has the 3. 42 gears and the mileage increase is only on highway trips, around town and short drives there's not enough difference to warrant discussion, I seem to get the best mileage with the smarty jr set at 40



we had exhaust brake noise which ended up being a cracked exhaust manifold at 94k which was replaced under warranty, I'm glad we waited until 100k plus to do the delete



my son deleted his 11' at 2,000 miles, I don't know if I would have the stomach to take that risk

 

[mpaulson]

So far the 4. 56 gears have had no negative effect on ecomomy, just a serious performance gain while accelerating. I'm better that this week coming up when I leave for my holidays to the mountains I will see some slight increase in mileage due to the easier effort for the engine. It's like starting out in low range. At hiway speeds empty, the egt temps are about 60 degrees lower, load percentage is averaging 20-25% instead of the 35% I had with the 3. 73, boost rides at about 15 psi instead of 22psi, so I'd say I've got the engine in it's sweet spot at 110kms/hr in 6th gear.