Great engine and transmission combo. Duramax / Allison ran well for most of the 10 years I owned the truck. Was used as a work truck with a contractors body fitted. Weekends was used to haul a 3 horse trailer. It worked every day of it's life with me. Poor build quality was evident in the front hubs, bodywork (rusted cab corners and rocker panels, roof flexing with windows open) and cab interior (gauges gave up, blower motor repeatedly died, gauge cluster lights died one by one, headliner fell off). Diesels are expensive to maintain when things go wrong, in my neighborhood it is hard to find a reputable diesel mechanic. Normal maintenance (oil change etc.) is probably more expensive but less frequent. All in all a very reliable truck that felt more like a car to drive.
I've had my 2500HD for just under a year now and I LOVE it. The only problem I really have is its fuel economy. I average around 14 mpg, but where it lacks fuel economy it makes up for it in power. I haul around a skidsteer on a 14 ft open trailer. The skidsteer weighs more then my truck but still no problems pulling it. The fuel economy doesn't really change weather your hauling or not. I just purchased an SLR performance chip that should do the trick. This truck is perfect for anyone with the money to pay for gas.
The interior is amazing. Comfortable enough to live in. Plus I got the BOSE stereo package and I love to listen to my rock with these banging speakers.
I have owned this truck since new in 2003. Only in the last several years have I used it to its full potential. I have pulled a 10,000 lb fifth wheel to Florida twice and a new 12,000 lb fifth wheel to GA last week and I averaged a little over 13 mpg. On the return trip I got over 24 mpg running at 70 mph all day. I do have a tonneau cover for the bed which might help. I first took this new truck to Ohio in 2003 and only got 22 mpg with the same configuration. I did add a K and N air induction system before my last trip but this truck pulls like a champ without any additonal brains or Banks kits. The 5 speed transmssion is smooth and I know improvements have been made in the 09's.
I think the duramax engine and allison transmission make this truck special.
When I bought it I had onstar and xm radio. I could not upgrade the onstar because I had analog and the xm i can do without.
The torque and power of the 8.1L is incredible, but be aware at the gas pump. An average of 9.1 mpg will be all you'll get. Towing large campers or trailers is no trouble what-so- ever. Especially in lower range gears the 8.1L begs for more. All around I love the truck, including a great interior and stock stereo.
Power, comfort, heated seats
Mileage gain of any would be great. GM needs to get on the ball with some reliability issues.