Used GMC Sierra 1500 Denali for sale near Walnut, CA

Aaron has been very courteous and professional during my contact with the dealership. He's gone above and beyond in his approach to customer service.

Great truck to own. The 2023 GMC Sierra Denali with the 6.2L engine delivers excellent power, smooth performance, and a refined driving experience. The ride quality, interior comfort, and overall build quality are outstanding. I have had no issues whatsoever, and it has been a reliable, enjoyable vehicle from day one. I would highly recommend it to anyone looking for a premium full-size truck.

This place is super legit. Bought my New Benz GL63 Amg. Shawn, Bang, Erika, Marlene and Tom all helped us out. They treat you like family here. Will be coming back with my wife to get the Bentley Gt.

This truck is the base model and that is exactly what we were looking for. A good solid truck without all the fancy technology. It drives like a dream, handles just as well and the interior is sleek and well designed. Perfect black on black exterior.... a man's truck.

The experience was Great! Mr Lozano is a great salesman, he helped me with all my questions, all the process was very smooth and simple, all the team is great from Lozano, Tony and Yuri great people, I?ll comeback to do more business with them

I own a 2023 Sierra 1500 Elevation equipped with the 2.7L TurboMax, and it’s been outstanding. It currently has 23,000 flawless miles. I’ll admit, I was skeptical of the 2.7 at first, but I jumped in feet-first and have never looked back. Living in Colorado, I regularly tow a 5,000-pound travel trailer through the Rockies with zero performance issues. The truck pulls confidently, handles grades with ease, and still delivers impressive fuel economy—23–24 mpg on the highway and about 18 mpg in town. I couldn’t be happier with this setup. If there is a negative to mention, that would be that after three years of ownership, the black wheels havent grown on me, and Im beginning to hate em. :) Lastly, the mpg while towing drops to 9mpg which is similar to that of a V8. All said, its been a great truck. :)

Let me start by saying I have the AT4 model with the Duramax 3.0L diesel. I had a 2024 Elevation with the 5.3L V-8 that I bought to pull my 22’ camper. While the Elevation pulled my camper fine it drank the gas like it was on a binge. And with a 26 gallon gas tank it seemed I was filling up every couple of hours. After one trip to Nova Scotia I knew something had to change. I pulled my camper out west to Yellowstone and back through Arizona. It pulled like a champ and fillups were a lot more manageable. Even driving the speed limit out west I still got four to five mpg better than with the gasser. I liked the Elevation but I love the AT4. Way nicer ride and great handling. I get 30 per gallon of diesel on the highway if I drive the speed limit but I got it to tow with. I added a Titian replacement fuel tank so I have 43 gallons instead of the 26 it came with.

Bobby and Mark were super nice and super friendly. They asked what was my budget and suggested cars that were with my range.

Stong engine and smooth! Highly recommend for familys or someone who likes a smooth truck. Purchased new and have had zero issues since then. Love it!

Jack in the service department came through for me in getting my front and back brakes done in a timely matter. Always responded to my calls. Awesome customer service.

Got the duramax diesel and getting 24 city and 32 highway is very good. Truck drives nice and is very comfortable. My 2 issues with this truck is the backup camera at night is useless (very dark) and interior lighting is not very good. You would have thought a 78k truck would have footwell lights, but it doesn’t.

Christopher is a great salesman and helped us get into the vehicle we wanted. Was very patient explaining details about the car since this is our first electric vehicle

Am in disbelief every week at the Gas Pumps. Thou a big truck, mileage per gallons are 18 +. Last week it was 22.8. This week 19.78.

Tustin Buick gmc went above and beyond my expectations. Super friendly and helpful staff. They were able to answer all my questions and concerns. I would definitely recomend buying a vehicle from this dealership. Thanks again Tustin Buick gmc for all of your help.

I have a 2023 GMC Sierra 1500 Denali with the 3.0 Diesel engine. I have 20,000 miles on it at the time of writing this. Never owned a diesel before and now i don't think i will own another one without it. I LOVE the engine in this truck. Only complaint would be that it likes DEF fluid while towing so pick up some extra DEF before you head out to tow something. Put about 8K miles on it this summer without adding any DEF fluid. seems to use a little more in the winter or when towing. Very quiet for a deisel and the fuel economy is awesome. Driving 70 mph down the freeway this truck gets about 30mpg, Drive 55mph on regular highways and this truck gets almost 40mpg. All around driving for me is about 26mpg. I used to fill up twice a week with my gas motor and now only once a week. Wireless Apple Carplay works great and the voice texting and mapping is a big plus. I also have the new SuperCruise feature which is awesome. Get on the freeway and set the supercruise on and the truck drives itself until i get to my exit (about 28 miles from home to work). Bose stereo is out of this world and all the storage is great to. I have a swingout bed toolbox, aluminum roll up tonneau cover, Lighted black GMC front emblem, Gloss Black 22" wheels, All Black decals and my dual exhaust bezels are black as well. I rotate the tires and change the oil every 5,000 miles. Couldn't ask for a better truck. Might get the ultimate next time as that has the messaging seats which i kinda wish I had.

Love this place , love the service, love how fast my process was to get into my M4 .best dealer I’ve ever made business, super polite , humble and very respectful, they even car washed the vehicle, man come one I was like whatttt!!! Super happy I drove out from Hollywood and I was not disappointed. Check it out for yourself!!!!!!

Any reviews on this vehicle is not correct. We are first owners and it’s been an excellent truck. We hate to see it go !

My truck was service and clean in the time promised. The service advisor are allows courtesy and helpful. The dealership and waiting area is clean and easy to assets

Does anybody else’s truck just sit there after you put it drive? I have to bump the accelerator to have it go into gear. ??????????????????????????????????????????? ?????????????

Pretty great experience overall. My sales representatives Maria and Rene were very helpful, answered all my questions and made the whole transaction quick. Highly recommend STG Auto!

Kris was great! Had a lot of patience with me and definitely will recommend him for your next car purchase.

My 2022 GMC Sierra 3.0 Duramax pickup truck is a good truck. I work on a farm and I also drive an hour to see my girlfriend. For the farm, it has excellent towing capability and for the hour long drive to go see my girlfriend, depending on the weather for traveling, I can get up to 35 miles to the gallon!

They been really good to me !love my car runs great .pablo was very nice an friendly

handles and drives great, the electronics don't always work, mirrors don't always work, spray with wd 40, check engine light, EVAP culprit, auto nation has no luck with this, will drive it till the warrenty expires and its back to ford for me

Hello GMC Team, On February 28, 2026, I posted a review regarding my experience at Tustin GMC, specifically concerning the inclusion of add-ons during the purchase process. In my review, I shared that I felt pressured when I was informed that a protection package valued at $4,200 had to be included in order to move forward with the deal. Today, March 1, 2026, I received a call from Tustin GMC management apologizing for the miscommunication. They explained that it was not their intent to pressure me, and that the final price presented actually included an extended warranty rather than a mandatory protection package. I appreciate the clarification and the outreach from management. I accept their apology and want to acknowledge their effort to address the situation and make things right. This type of follow-up and accountability is what excellent customer service is all about. Thank you to the GMC team for taking the time to reach out. Your actions truly go a long way.

We have owned our GMC Sierra 1500 for approximately 9 years now. The only real disappointment with the vehicle is that we had to have a full transmission replacement Just after the 100k mile without any warning whatsoever. The truck now has 107k miles on it and now , again out of nowhere, we are experiencing slipping in the trans and the engine light is now flashing. Very disappointing since we are starting to feel uncertain about the reliability of the vehicle now. The truck itself is gorgeous and shows ZERO signs of its age, sporting new rims and tires and a lifted body and no rust on the body at all. We hope there are no major issues with the engine as the vehicle has always been maintained as needed and on time for regular servicing at the dealership.

The prices attracted me. The customer service and experience/ level of knowledge was not great. There was an inconsistency of dealership policy. It would be nice to get a car for the price you expect. I felt forced to purchase items I did not want

I love it the look the interior mine is a red one and it looks so good and it’s my baby and it runs so good and the technology is off the chain

Alex G is probably the most helpful car salesman there is. Not only did he make sure to really do everything he could to get me a great deal on a car I actually wanted, but as a first time car buyer no other dealership or car salesman wanted to seriously help me, but he did. I can’t recommend Alex enough at this dealership.

This truck has a jerk when changing gears sometimes. I enjoy the truck overall easy to handle and comfortable. Drive with ease sight is good when driving.

2024 GMC sierra 1500 duramax 3.0 is great truck. Great ride and great MPG. 100% recommend to any prospective buyer. Love the truck and how it perform.

Trey helped my husband and I get our first family car! The process was easy and the deal was great!

Man this place is one of the best place in California to buy a car they are super legitimate and will work with every situation and story. They treat you like family first before you’re a customer. All there cars are super fire and they make it happen. If you looking for a car this is the best place to go manager Sean is so down to earth and will make it happen. Thanks lsm cars

2021 GMC sierra 1500, 5.3, crew cab 4x4, 21000 miles. brakepad monitor lites up. dealership says needs brakes and rotors in back. one mo. on warranty. our rural roads dirty up the monitor. Needs new monitor. brakes look great to me. No noises. dealer says parts on order GM strike. Can't replace myself cause of computer...

Nate was the best he definitely went above and beyond and made sure I was getting everything that i wanted he also went out his way in told Me personal stories on the cars what I wanted to give me a better visual of the car and if it was for me , he didn’t just try and tell me what ever to get me to buy what ever he made sure to get me to buy a car that I truly wanted so Nate ! Was the best and I would definitely recommend him for a confused car buyer . Thank you

Waiting for the Refreshed 2022 AT4 was well worth it! With all the manufacturing issues today, building and shipping was slow, but understandable. Love the truck and the features! Fit is perfect and quality is #1. Pricing was too high but all vehicles are running this way. You get what you pay for and this truck is perfect! I have owned many trucks and this by far is the best. The latest features are beyond most other makes and GM has thought this truck through from front to rear.