Standard STS features include leather upholstery, aluminum interior trim, dual-zone automatic climate control, Bose AM/FM/CD stereo, interior auto-dimming rearview mirror, OnStar telematics (with one year's service), StabiliTrak electronic stability control, automatic high-beam control (Intellibeam) for the headlights, rear park assist and the usual lineup of power assists, creature comforts, extra conveniences and driver aids.  

Optional packages for the V6 model include the V6 Luxury Package ($3,540) with two-position memory for seats, mirrors, climate and radio controls; Rainsense wipers; six-disc in-dash CD changer; Sapele wood trim on the instrument panel, steering wheel, console and center stack; heated and ventilated front seats with four-way power lumbar; heated rear seats; heated steering wheel; tire-pressure monitor, universal home remote; and a cargo net.   Other packages include the V6 Luxury Collection ($4,500), a V6 Luxury Level 2 Package ($3,950), a V6 Premium Luxury Collection ($2,740), a V6 Platinum Edition ($7,950), and a V6 Premium Package ($9,100).   Options for the V8 include the V8 Premium Luxury Collection ($4,655), V8 Platinum Edition ($6,500), and V8 Performance Package ($12,440).  

Stand-alone options, included in some of the packages above, include Performance Handling ($1,600), power moonroof ($1,200), Performance Brakes ($395), DVD rear entertainment ($1,985), 18-inch polished alloy wheels ($600), and enhanced StabiliTrak with active steering for the V8 ($995).   A Bose 5.1 Studio Surround Sound system with six-disc CD changer and DVD-based navigation is available.  

Safety features that come standard on all models include dual two-stage frontal airbags, front seat-mounted side airbags, front-and-rear side-curtain airbags, anti-lock brakes, StabiliTrak electronic stability control, tire-pressure monitoring, and OnStar; its operators will contact appropriate assistance if there is an airbag deployment (meaning the vehicle has been in a wreck), and the passengers don't respond to calls.  

Lane Departure Warning uses a camera located between the inside rearview mirror and the windshield to detect lane markings on the road and alert the driver when the vehicle inadvertently strays from the intended lane.   Side Blind Zone Alert uses radar sensors behind the rear fascia that signal an audible and visual alert if objects are detected where it might be difficult for the driver to see them.   Enhanced StabiliTrak with active steering is available only on V8s with AWD.