Used GMC Sierra 2500 AT4 for sale near Diamond Bar, CA

Fantastic dealership with professional and courteous staff.

One very awesome vehicle. Checks all the boxes you need in a truck and exceeds expectations on quality, performance, and looks great ,too. Love my nre truck.

3 recalls required, 2 requiring parts. Confirmed parts onsite and scheduled service. Service writer wasn't available on arrival and another associate took responsibility immediately. Courtesy shuttled home, was called when service was done and shuttle picked me up, all taken care of in less than 1 day. All personnel were friendly, courteous and responsive to my concerns. Very good experience regarding all aspects of service. I recommend MK Smith.

I paid over $106,000 for this truck with warranty. Do not care much about miles per gal. at that that price range. Just too much truck for me at my age.

I went in to have an oil change, Oil change was completed in a timely manner. I waited in the waiting room which was very clean . My vehicle was washed , very good customer service

Love everything about this Duramax Denali except the fuel mileage. 13-14 Mpg tops when not towing. Bought truck cause previous was stolen. Wish I still had my 6.2 High Country!

Enjoyed my experience here at this dealership. Came out with a brand new car! Anthony was extremely helpful and guided us to find the car we were looking for.

So far so good! This truck is the nicest truck I have ever driven. The stance, ride comfort and options are top notch. I went from a 2023 High Country that was having drive train issues but had all the creature comforts that you would expect in a top of the line truck. With the lack of confidence in that particular models 10 speed transmission issues, it became necessary to reestablish my confidence in my General Motors product.

Xavier, Sebastian, Aaron, and Nicole were all helpful and good to work with! Thank you!

My online salesman Xavier was great! I live 2,000 miles away, and the whole transaction was done on my phone, and within 24 hours. Having to come up with a shipping company was the hardest part of the process.

Overall, I had a good experience purchasing my vehicle here. Thank you to Wes for being so kind & helpful!

I've owned every other American truck and this is my first GMC. I bought the 2500 HD Texas Edition. I absolutely love this truck. It's everything I could have hoped for and more. It is able to pull my 30' travel trailer with no problems. So now when we go out with our trailer I'll have no worries. The look and feel of the truck is outstanding. The 6.6L gas engine actually gets great gas mileage. It gets about the same as my Ford f150 ecoboost. Probably better on the highway. Looking at about 13 miles in the city and 15 plus on the highway. Definitely got a better truck for the price compared to any other american models with the same characteristic and options.

We were helped by Wes and Marvin, they are great people with a very good personality as they were very helpful going over all the details and questions we had A+ service

Professional and superb customer service. Was dealing with a check engine light. They go out the way to make sure customer is taken care off.

I highly appreciate the professionalism and efficiency at STG Auto Group. Maria made sure I was accommodated throughout the whole process. She was polite and always elaborated when I had questions. I’d highly recommend going to STG Auto Group for your next vehicle purchase. Ask for Maria, she made it easy.

I flew in to make the deal on a 2017 Yukon Denali XL! It was priced right and very pleased with outstanding customer service!! will definitely do business again with them.

This truck is the truck that all others should look up to. It rides great, will tow a house, runs smooth, and gets great fuel economy. The Allison transmission is so smooth. The AT4 looks great too.

Experience was excellent! Everything was so smooth and easy! We are so happy with our purchase! Highly recommend Danny from GMC! Customer service was on point!

What a gorgeous truck, runs good, sounds good and has all of the amenities I need although I am looking forward to their next interior upgrade.

The staff was very helpful and attentive. They took pride in the dealership and the vehicles. Everyone was friendly to my family. I would definitely recommend this dealership.

Dominique is very good customer service in my buying today for the Ram 2500 working with him was very easy

Great power and yet great economy. Love the safety features with the cameras and side vehicle warning. Camera that shows side of vehicle, including trailer when turn signal is on is great. Also appreciate the bed camera for hooking up gooseneck trailer.

Well, our experience with Tony was Fantastic! We found a car on the internet that we wanted and proceeded to go out there to purchase. Upon our arrival, Tony greeted us without delay and processed our request. We were out of the dealership within 1.5 hours, now that's a record! He got us our approval in a timely manner and it was all good!!! I would definitely work with them again. Now about the markup, it seems all the dealerships mark up and in order to stay in business so I don't worry too much. Plus the fact the car we purchased was in pristine condition with low miles it was worth the markup and the drive. I am a satisified!

I have not went to see a car yet so I will be there on sat

I love my 2021 GMC Denali 2500HD. I have gotten more complements on this truck than any other vehicle that I have owned. I get great highway fuel milage average 19-26mpg,which is great for a heavy duty truck!