The Sierra gets a revised look this year that includes a new front fascia, revised side moldings and an additional wheel design. Top-of-the-line models get power-folding heated mirrors with puddle lamps and turn signal indicators. Inside, the Sierra now offers a Bose stereo system and XM Satellite Radio. The instrument panel and center console have been redesigned, and GMC has added new seats, a more comprehensive driver information center, optional satellite steering wheel controls and a dual-zone climate control system. For increased safety, Sierras now feature a standard front-passenger-sensing system and dual-stage airbags. All 4.3-liter V6-equipped Sierras and California-emission V8s are now ULEV certified, while electronic throttle control is now standard on all V8 engines. Finally, the Autotrac four-wheel-drive system has been modified for less intrusiveness at low speeds, and the brake system received upgrades that provide better pedal feel and improved overall performance.