From the Dealer using my truck to tow the owners horse trailer and adding 100 miles to it...to the more than $3000 I had to put into the electrical within 3 months-to the instrument panel stopping to work (speedo, then oil pressure, then battery-which comes and goes) $900 fix it so I just use a GPS for my speedo-to the rattle in the steering because of design issue always going out....to the electric seat positioning clicking 7-8 times before settling into place-to now the heater/AC blower stopped working and a cost of $750 to fix it at PEP Boys.
Thanks to youtube the heater fix will only cost me $150 in parts.
(my friend just had the same thing happen to his Tahoe and had to pay $750.
The diesel itself is great, when running.
I love the size, the big interior, the carrying power.
The reliability and the response from GMC are the only problems.
(if I received the support I would expect, I would be #1 supporter of GMC)
I do not/cannot trust any of the dealers and the customer service person in Detroit (or where ever they reside) "almost" helped me but ended up not helping.
I will never buy another GMC as long as I live and will tell all that I know of the problems that I have seen with the company.
I believe there should be more monitoring of what goes on at their dealerships, better selection process or something.
And, stand by their design flaws.
Proactively, not reacting to a crisis before something is done.
(cannot be a coincident that my friends and my heaters went out at the same time.
(PEP Boys told him that happens "a lot" with these.
I purchased the Sierra dually Duramax (LLY - 310hp & 605flbs) to pull a heavy fifth wheel and so far my experience has been trouble free. So far I am fully satisfied although I only have 30,000 km and time will provide more information on reliability of the Duramax. I find it fun to drive and fuel efficiency is good compared to the other diesel (Ford & Chrysler). It provide plenty of performance compare to a gas engine. The interior is perhaps blend as per the critics but it provides a price advantage compare to the Ford's King Ranch. It does not take away from the performance.
I think that the Allison transmission is the main feature of the truck. The exterior design around the dual wheels has a more aerodynamic appeal.
The interior design could be improved but not at the expense of reliability. There are after market products available to increase output (hp & torque) that I wish GM would test and permit without invalidating the warranty.
† Edmunds.com received the highest numerical score in the proprietary J.D. Power 2014 Third-Party Automotive Website Evaluation Study℠. Results based on responses from 3,381 responses, measuring 14 companies and measures third-party automotive website usefulness among new and used vehicle shoppers. Proprietary study results are based on experiences and perceptions of owners surveyed from January 2014. Your experiences may vary. Visit jdpower.com.