The 2012 Sierra 1500 lineup includes everything from the job-ready Work Truck models to the Sierra Denali. Regular, extended and crew cab models are available in Work Truck, SL, SLE and SLT trim packages in two-wheel and four-wheel drive. Vortec engines use "vortex technology" to mix the incoming air and fuel for enhanced performance and fuel economy. The powertrains are backed by fuel-saving six-speed automatic transmissions. A Z85 handling/trailering suspension is included on Work Truck models with the trailering package. The StabiliTrak stability control system includes electronic trailer sway control and hill start assist.