GMC's full-sized trucks are all new for 2007. The Sierra is offered in regular, extended and crew cab configurations with 3 bed lengths. Two-wheel and four-wheel drive versions are offered across the line. A total of 8 different engines are offered, many with cylinder deactivation technology for increased fuel economy. Flexible fuel versions allow for ethanol running. A four-speed automatic transmission is retained in all models except the range-topping Sierra Denali. The front suspension is a new coil over shock design. Solid axles are retained in the rear. Five different suspension packages are offered for various duty requirements.