2021 GMC Sierra 2500 HD

The base Sierra 2500 comes with 17-inch steel wheels, LED headlights, LED daytime running lights, and LED taillights. A step up to the SLE adds 17-inch alloy wheels and the MultiPro tailgate, while the SLT has LED fog lights. The off-road-ready AT4 comes with all-terrain tires, 18-inch wheels, and an Eaton locking differential. At the top of the Sierra lineup, the Denali adds 20-inch alloy wheels, side steps, and chrome exterior trim.

The standard engine for the Sierra 2500 is a 6.6-liter V-8 that puts out 401 horsepower. It works with GMC's six-speed automatic transmission and comes with rear-wheel drive. All-wheel drive is optional for any trim except the AT4 and Denali, where it comes standard. A 6.6-liter V-8 turbodiesel is an optional powertrain if you want its 445 horsepower and 910 pound-feet of torque. This engine uses a 10-speed automatic transmission.

This truck has the power to tow up to 18,500 pounds when equipped with the turbodiesel and the tow package. It can also haul up to 3,863 pounds in the bed. It's independent from suspension provides a smooth and comfortable ride, and even though the truck feels big, it is easy to drive and it's easy to maneuver.

There's room for up to six in the Sierra 2500, depending on the cab. The entry-level trim has a front bench seat, manual windows, and vinyl seats. The SLE adds cloth upholstery, more storage options in the cabin, and power door locks and windows. The more upscale SLT comes with a power-adjustable driver's seat, leather upholstery, and dual-zone automatic climate control, while the Denali has premium leather upholstery.

Technology features in the 2500 start with a 7-inch touch screen, Bluetooth for up to two devices, and Apple CarPlay and Android Auto. Satellite radio is an added tech feature in the SLE, and the SLE comes with an 8-inch touch screen and wireless Apple CarPlay and Android Auto. Moving to the top of the lineup gets you a navigation system, an upgraded Bose stereo, and an upgraded driver information display.

Every Sierra HD comes with a rearview camera and the Teen Driver system. The SLE adds OnStar emergency communication services, and the SLT comes with GMC's ProGrade Trailering system, an In-Vehicle Trailering App, and Hitch Guidance with Hitch View. The Driver Alert I package adds front and rear parking sensors, lane-change alert, a blind-spot monitor, and rear cross-traffic alert, and the Driver Alert Package II comes with automatic high beam headlights, lane-departure warning, and a following distance indicator. A head-up display is also available, and you can get forward collision warning, a surround-view camera, and automatic emergency braking.