Vortec 4.8L V8 SFI, 4-Speed Automatic with Overdrive, and 4WD. Brilliant build quality. Exciting acceleration! Set down the mouse because this attractive 2006 GMC Sierra 1500 is the low-mileage truck you've been hunting for. J.D. Power named the 2006 Sierra 1500 as the highest ranked in Overall Initial Quality Design in its class. It's the combination of advanced design and precision engineering that makes the Vortec 4.8L V8 SFI engine such an impressive powerplant.