GMC Sierra All Terrain HD Concept: Diesel-Powered Off-Road AwesomeMatt Hardigree12/16/10 5:30pm4401EditInvite manuallyPromoteDismissUndismissHideGo to permalinkThe GMC Sierra All-Terrain HD Concept's a badass, no doubt. It's big. It's macho. It's American. And unlike the Ford Raptor or Ram Power Wagon, you can get it with a diesel engine.