Well I just picked up my 05 Duramax today and I have only put about 40 miles on the truck, but when I was checking the computers esitmated MPG (miles per gallon) on the control center it said I was getting about 10.6mpg. That sounds very low to me, or does the engine need to be run a little bit first before the MPG get up there. I was told I should be getting at least 20mpg from friends that have duramax's.
Jeff, I got my new D/A 2 weeks ago. Drove it on a 300 mile trip, the first 30-40 miles the reading was only 15 mpg. By the time I got to 300 it read 19.7 and thats at 65 mph. I hand calculated it and it was 19.2, still pretty good for a new engine. They say it will get better with the miles. This is one nice truck.