Used 2008 GMC Sierra 2500HD Consumer Reviews
I traded in a 2004 F150 4.6L with 25,000 miles to get a 2008 GMC 2500 6.6L diesel. The performance is unreal. I am getting over 13 mpg, which is the same as the 150 on Premium and I get 3 times the power. The ride, fit and finish are as good or better and the information center is a real boon. The shakedown will continue for another six months but for the first 30 days I could not be more pleased.
This is a decent truck, but NOT with the 6.0 and GM 6 speed. You HAVE to get the Duramax if you need a 3/4 ton truck. The gas motor with fly by wire throttle, and GM 6 speed, is a horrible combination. It is a death trap when trying to merge with traffic, especially in conditions when you are on and off the throttle. There is up to a 3-4 second lag where absolutely no throttle input is given to the engine, no matter how hard you press on the accelerator. I believe GM implemented this so their tranny wouldn't explode. The engine and tranny computer work together, and the tranny computer tells the engine computer to not give any throttle until the tranny is ready (it never is).
I love this truck but when I am not towing or under load she will shake you on bad michigan roads. I decided to weigh it down a bit in the back and that has smoothed it out for sure. MPG is 12. 12 @ 74 towing the boat, 12 at 35 around town. I got 14 on the highway going 65 but that was hard to take for a 2mpg gain. Love the solid feel of the truck!
This is definitely a Cowboy Cadillac. Performance wise, the gas V8 has all the power you'd need and tows my 7K # trailer with ease. The tranny shifts smooth but as another reviewer said, make sure you get the TCM flash for better kickdown response. The 2500HD 'pure pick up' interior on the SLE not only looks great, it's durable and functional as well. The front seats are great for long road trips. I'm getting about 12 mpg around town and up to 17.5 mpg highway at speeds up to 65. Above that, it nosedives into the 12-14 range. Overall, I'm completely happy with my truck after 15 months. I've had no problems and plan to keep this for a long time.
This vehicle was a replacement for a 2005 2500HD Duramax SLE and the engines are nothing alike. The new Duramax and six speed Allison is quieter, smoother and the towing power is incredible. We are towing a 35 foot travel trailer and it is like there's nothing behind you. The Z71 package does increase the stiffness but the ride is excellent. The interior rivals my '07 Denali. If you gotta tow, this is the one to buy.