That includes the GMC AT4 sub-brand, which is available across almost the entirety of Big Red’s lineup. The question, then, is this – what does AT4 actually stand for? As it turns out ...

For off-roading fans, the GMC Sierra AT4 delivers thanks to enhanced, trail-ready capability and a rugged, aggressive design. Highlights of the factory setup include a two-inch lift, all-terrain ...

The 2019 GMC Sierra AT4 proves that GM's upmarket truck and SUV brand is getting serious about offering rough-and-tumble capability to rival the Ford F-150, Toyota Tundra, Ram 1500 and Nissan Titan.