The Sierra gets a revised look this year that includes a new front fascia, revised side moldings and optional multifunction, fold-away mirrors. On the inside, GMC has added new seats, a more comprehensive driver information center, a redesigned instrument panel and optional dual-zone climate control and satellite steering wheel controls. On the hardware side, the standard 6.0-liter V8 gets electronic throttle control as well as the ability to run exclusively on compressed natural gas (CNG) or a mix of CNG and gasoline. Other upgrades include an improved Insta-Trac part-time four-wheel-drive system for reduced service costs, a more efficient starter for the 8.1-liter V8 and a revised headlight switch that allows drivers to turn off the daytime running lamps.