Poor fuel mileage

[cos]

Hey guys.... I cant believe the horrible fuel mileage im receiving on my new 5500's. Im pulling a 16k trailer that used to be behind my 3500 (which averaged 10 mpg) and now im lucky to get 7.5. Usually its closer to 6.8 - 7.0 mpg. Any suggestions on how to increase mileage? Ive got two of them, and im loosing money every mile!!

[markrinker]

I would imagine that it is directly related to your gear ratio. Depending on what you have, it could easily account for the difference between the C5500 and your light duty 3500 series truck.

Another significant factor is frontal area of the trucks. The C5500 wind resistance is significant in comparison to the 3500 series light duty truck.

Hopefully, you are making use of the additional towing and hauling capacity, and making more money per mile as well.

[ksss]

I was equally not happy with the mileage. I added a programer to mine from Pacific Performance. My empty mileage went from 8 mpg to 13.5 and I got more power. I have it set on the first setting which is 60 hp. The only issue is that the unloaded mileage only went to 9-10 depending on how heavy I am.

[cos]

Do you have a number for Pacific Performance? I tried doing a google search and couldnt find it... any info would help.... I figured today that at $3.30/gallon over the course of one year, these two new trucks will burn $30K extra in diesel!!! I could hire a whole other person for that! Also, I thought about hauling a larger trailer, but lets face it... do I really want to put a 33,000 lb. trailer behind one of these trucks? Black and white specs say no., plus, I couldnt afford the downtime if I beat on them like that...

[markrinker]

What gear ratios are these trucks running? I am interested in a 2006 C4500 2WD with 3.73 gears.

What mileage should I expect with the LLY and 6-speed Allison combo?