Used 2021 GMC Sierra 3500HD Consumer Reviews
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We have a limited number of reviews for the 2021 Sierra 3500HD, so we've included reviews for other years of the Sierra 3500HD since its last redesign.
WHAT A TRUCK
Bill S., 04/06/2020
updated 04/08/2021
2020 GMC Sierra 3500HD Denali 4dr Crew Cab 4WD SB (6.6L 8cyl 6A)
25 of 25 people found this review helpful
I purchased this Denali two weeks ago. I absolutely love this truck. The ride is so smooth and power band is incredible. What a huge difference between my 2008 GMC 2500HD Duramax, its like night and day... I love all the high tech features with the 2020's from the cameras to the front and rear LED lighting. Oh yea forgot about that first of its kind tailgate. Now that's a very useful tailgate, I can see Ford, Dodge and Chevrolet using the same basic tailgate in the near future. I really cant wait to haul my 5th wheel with this truck. Once I make that first trip I will update this review regarding the towing... A big thank you for Thompsons GMC in Placerville, CA for such a great purchasing experience. It’s been about a year since I purchased my GMC 3500 Denali and wanted to update my review. I still love this truck so much. I’ve towed my 5th wheel RV approximately 8000K miles. This truck tows my 5th wheel like a dream. The cooling system is definitely a 100% improvement over my 2008 while towing in the warmer weather. About the only thing I’d like to see is GM add more information to the heads up display (HUD) like your blind spot indicators. I’m glad we bought when we did because I hear that dealers are having a tough time receiving new trucks. Bottom line is this, I’d buy this truck all over again absolutely No Regrets!!!!
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Heavy Duty tuxedo surpassed expecations
Corey, 08/30/2020
updated 09/07/2023
2020 GMC Sierra 3500HD Denali 4dr Crew Cab 4WD SB (6.6L 8cyl 6A)
12 of 12 people found this review helpful
In my 3rd year of owning the new 2020 GMC 3500 HD Denali after replacing my 2012 F250. Choose the GMC because I did not care for the new Ford styling. I still can not believe this is a HD 3500. While commuting around town, I think I am in my wife's German SUV because the ride and amenities are excellent. Visibility and Camera system are great and the interior seats comfortable and supportive. When I hooked up the 3x axle boat and set out to the lake I was amazed at the poise and power. It made towing enjoyable! I really like my F250, but this truck is awesome.
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2021 GMC Sierra 3500HD for sale near you
Showing 3 of 231 listings
- AT4 Diesel Crew CabMSRP: $60,99073 mi away
- Denali DieselMSRP: $58,99576 mi away
- Denali DieselMSRP: $61,89883 mi away
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Incredible
Ron, 03/13/2020
2020 GMC Sierra 3500HD Denali 4dr Crew Cab 4WD LB DRW (6.6L 8cyl 6A)
11 of 13 people found this review helpful
After waiting for several months and production delays I was finally able to get my hands on a 2020 3500 Denali DRW and I have to say that this truck was well worth the wait. It drives smoother than any truck I've ever owned and the safety features are incredible. I have absolutely no complaints and with it being a Denali there really isn't any more stuff I will need to add. (other than a fifth wheel hitch) I love the 10 speed transmission and the 6.6 diesel has more than enough HP and torque. GMC hit it out of the park!
Trailer issues
Mario, 09/13/2021
2020 GMC Sierra 3500HD Denali 4dr Crew Cab 4WD LB DRW (6.6L 8cyl 6A)
7 of 8 people found this review helpful
Extremely disappointed with my 2020 Denali 3500hd. I own 6 trailers and only 1 works with the "new" trailer integration system. I get trailer not connected display, brake lockup on connecting, flickering lights. Trailers work perfect on other rigs. GM dealership basically said to pound sand and update my trailers to work with their system.
Good!!!
Shasong, 07/12/2020
2020 GMC Sierra 3500HD SLE 4dr Double Cab 4WD LB DRW (6.6L 8cyl 6A)
4 of 8 people found this review helpful
I have one, purchased in 2017, used for pulling boats and RVs. It ran more than 50,000 kilometers, with strong power, low fuel consumption, and no trouble. It is a very very good car.
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What a BEAST
Dave, 08/17/2023
2020 GMC Sierra 3500HD SLE 4dr Crew Cab 4WD SB (6.6L 8cyl 6A)
1 of 1 people found this review helpful
Drove this truck 1,000+ miles up and down crazy steep grades through the Rockies and all over the Southwest pulling a 32ft trailer. This thing handled it like nothing. What a breeze to drive.
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Impressed with this rig
John, 08/21/2023
2020 GMC Sierra 3500HD Denali 4dr Crew Cab 4WD SB (6.6L 8cyl 6A)
1 of 1 people found this review helpful
Ours is the Duramax. We traded out Tundra mid road trip because it was struggling with our RV. I am a Toyota guy all the way but this truck has been unbelievable. It is 7700 lbs and we get over 20 MPG easy. If I need to get on it to merge with traffic, it slams you into your seat. I have had over 500 miles on a tank with 240 of that pulling our trailer (and I still had 1/8th of a tank left). Oil change was less than I expected and finding diesel has not been an issue. I know there are significant issues with the lifters in the gas burners but not with the Duramax. Don’t shy away from this diesel truck. Our only issue has been with the nav, it takes some getting used to but once you bend to its will life is good. Hope this helps
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Great truck for towing!
Nick Odenath, 09/02/2023
2021 GMC Sierra 3500HD AT4 4dr Crew Cab 4WD LB (6.6L 8cyl 6A)
1 of 1 people found this review helpful
This truck is a beast when it comes to towing our 12k lbs fifth wheel. It is comfortable for the family on long trips and the tech inside is great!
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Awesome truck
WFlanigan, 01/08/2021
2020 GMC Sierra 3500HD SLT 4dr Crew Cab LB DRW (6.6L 8cyl 6A)
1 of 2 people found this review helpful
Best truck hands down !!! Work or play you’ll getter done as Larry says!!!
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Top running Lights!!!
GMC , 08/17/2020
2020 GMC Sierra 3500HD AT4 4dr Crew Cab 4WD SB (6.6L 8cyl 6A)
3 of 17 people found this review helpful
Why do they need to to put the running lights on top?? Think it makes it look cheap. Think looks more rugged without lights on top. Fender lights don't bother me although. Beautiful truck.
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Best truck I’ve owned
M Bammel, 04/27/2025
2020 GMC Sierra 3500HD 4dr Double Cab LB (6.6L 8cyl 6A)
0 of 0 people found this review helpful
Only issue I have is not GM’s fault. The emissions system hinders this truck’s true potential. Otherwise it has done everything I’ve ever asked it to.
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Great 1 ton dually w/30K lb 5th wheel hitch.
Full-timer, 01/02/2025
2021 GMC Sierra 3500HD SLT 4dr Crew Cab LB DRW (6.6L 8cyl 6A)
0 of 0 people found this review helpful
Great road tractor, with 6.6L Duramax, 10 speed Allison and a comfortable Cowboy Cadillac. Plenty of towing capacity. Barely broke in with 49K miles since new in April of 2021. Sold my 5th wheel RV so no longer need the dually.
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