I had a 2000 4X4 ext cab dually,8.1 with 4:10 - about 6-8 mpg. But I was loaded down with tools and ladders. Even removed the back seat for more space for storage. The back seat in those trucks is useless anyway. But it did tow excellently - didn't even know there was anything back there. I chose the gas engine for conveineince, and figured I could fill up anywhere. Good thing with that low gas mileage and long hauls.

Great truck, but lots of gas and to fill up took 15 minutes PITA!!

friend has the 03 same package , says he get's around 12 mpg

2001 2500HD crew cab, 10-11mpg not towing
7-8 towing 12000 lbs

8.1 liter with 4.10 gears

Power of the 8.1 compared to the 6.0 is night and day, plus you get the allison tranny.

I usually pull the boat at 70 to 75 mph, if you slow down to 65 mileage might be a little better.

Just for comparison purposes, towing back from the ozarks I have a friend with a dodge cummins pulling the same size boat, when we filled up and compared the mileage he was getting 11 and I was getting 8.

I tow with a 90' chevy 3500 dually, 7.4 tbi wit a turbo trans. Mileage towing 9-10. I have towed with my B-I-L
99' 2500 Burb, 7.4 Votrec. Mileage towing with that was 13-14. Both towed well. Used the Burb to pick my boat up, about 830 miles each way. Did the trip in 13.5 hrs out and 14 hrs return. No, I wasn't pumped!!!!!!!!

this is my 02 2500hd with the 6 liter...... i might get 10mpg.......with 2 bucks a gallon now.....i cringe every time i stop at the gas pump wich is quite a bit...but the truck other wise is great!....looks better than a phurd and beats them all in a drag race......coming from experience

I have a 2500 Suburban with 6.0 and 3.73 gears. It get's 11mpg city 12.5 highway, not towing

I have a 2000 3500 8.1 allison, 11 mpg non towing 8-9 with boat. Love the truck lots of power and rides great.

2500 Avalanche with 4.10 and I get 11.4 mixed highway and city. With my previous Av, it had the 3.73 and I got 14.1 on the highway.