0.0Advertised prices are valid as published but may change only to correct bona fide typographical or clerical errors. Where permitted by law or unless there exists a written warranty, all pre-owned vehicles are sold AS-IS WITHOUT FAULTS. Certified pre-owned vehicles include only those manufacturer warranties described in writing at the time of sale. Mileage shown reflects odometer reading at time of listing and may vary. Vehicle history reports are available upon request.
This 2021 GMC Sierra 1500 is the AT4 trim in a Crew Cab Short Bed configuration with the 4SB Preferred Equipment Group, finished in Summit White, showing 89,893 miles. It's powered by a 3.0L inline-6 Duramax turbo-diesel paired with a 10-speed automatic transmission and four-wheel drive with a locking/limited-slip differential.
This Sierra AT4 was serviced on 6/10/2026 with a maintenance inspection, along with checks of the A/C system, antifreeze/coolant, engine, and engine/powertrain computer a documented, dealer-prepared service record for the next owner.
This AT4 is built with the AT4 Value Package (front and rear all-terrain tires), the Technology Package (Aerial View Display System, heads-up display, back-up camera), Driver Alert Package I and II (Lane Keeping Assist, Lane Departure Warning, adaptive cruise control, Front Collision Warning and Mitigation, rear parking aid, Blind Spot Monitor, Cross-Traffic Alert), the AT4 Preferred Package with navigation, and the Trailering Package with a tow hitch. It also includes a sunroof, tow hooks, an integrated tailgate step, and the MultiPro Audio System by Kicker.
Inside, this Sierra AT4 offers heated and cooled front seats, a heated steering wheel, power driver and passenger seats with adjustable lumbar, and multi-zone climate control. Technology includes navigation, a WiFi hotspot, telematics, satellite radio, and Aerial View Display. Driver-assistance features include adaptive cruise control, Lane Keeping Assist, Front Collision Mitigation, Blind Spot Monitor, and Cross-Traffic Alert.
## Who This Fits
This Sierra AT4 suits buyers who want genuine diesel towing capability paired with off-road-ready hardware all-terrain tires and a locking differential without giving up heated and cooled seating or a full driver-assistance suite. It's a strong fit for someone who tows regularly and wants the diesel's torque advantage along with documented recent service.
## How It Compares
Shoppers looking at this Sierra AT4 often also consider the Ford F-150 Tremor, Ram 1500 Rebel, and Chevrolet Silverado LTZ Z71. Compared to the F-150 Tremor, the Sierra AT4's diesel engine offers a torque advantage well-suited to heavy towing. Against the Ram 1500 Rebel and Silverado Z71, the AT4 brings a comparable off-road-focused equipment list along with GMC's diesel powertrain option, a distinguishing choice in this class.
## Key Equipment
3.0L inline-6 Duramax turbo-diesel engine
10-speed automatic transmission
Four-wheel drive with locking/limited-slip differential
Front & rear all-terrain tires
Aerial View Display System
Heads-up display
Adaptive cruise control
Lane Keeping Assist / Lane Departure Warning
Front Collision Warning & Mitigation
Blind Spot Monitor / Cross-Traffic Alert
Navigation system
MultiPro Audio System by Kicker
Heated & cooled front seats
Heated steering wheel
Power driver & passenger seats
Multi-zone climate control
Sunroof
Tow hooks
Integrated tailgate step
Trailering Package with tow hitch
## Frequently Asked Questions
**Is this Sierra AT4 diesel?**
Yes, it's powered by a 3.0L inline-6 Duramax turbo-diesel engine.
**Has this truck had recent service?**
Yes, it was serviced on 6/10/2026, including a maintenance inspection with A/C, coolant, and engine system checks.
**How many miles does this Sierra AT4 have?**
This vehicle shows 89,893 miles.
**Can this Sierra AT4 tow?**
Yes, it's equipped with the Trailering Package, which includes a tow hitch.
**Where can I see this vehicle in person?**
It's available at Brickell Buick GMC in downtown Miami, Florida, serving Coral Gables, Coconut Grove, Miami Beach, and the greater Miami area.
Interested in this diesel-powered, dealer-serviced 2021 GMC Sierra 1500 AT4? Contact Brickell Buick GMC to schedule