Buick's version of the Chevrolet TrailBlazer and GMC Envoy remains the handsomest and most luxurious of its corporate cousins, with the most standard features. The standard engine is a 4.2-liter in-line six that now generates 291 horses, while a 5.3-liter V-8 engine that's been bumped up to 300 hp. and includes a displacement-on-demand feature to help conserve fuel is also available; both engines can drive either the rear or all four wheels via a four-speed-automatic transmission. Buick's "QuietTuning" system is on hand to help reduce interior noise and vibrations. As with Buick's upscale sedans, a host of systems, such as the power seats and mirrors, radio, door locks, lighting, and climate-control, can be personalized to suit multiple drivers' tastes. For 2006, GM's StabiliTrak stability-control system, integrated with traction control, becomes standard on all Rainier models. Exterior refinements for 2006 include chromed accents on the side roof rails and exterior door handles, along with a new grille design. In addition, Buick increased its bumper-to-bumper warranty coverage to four years or 50,000 miles on all 2006 models.