The Rainier comes in just one well-equipped trim level, called CXL. The Rainier is available with two-wheel drive and four-wheel drive. Standard equipment includes a four-speed automatic transmission, electronically controlled rear air suspension with automatic load-leveling, locking rear differential, four-wheel anti-lock disc brakes and dual-stage driver and front passenger airbags. Traction control is standard on 2WD models. The standard engine is GM's highly regarded Vortec 4200, an inline-6 that provides an impressive 291 horsepower and 275 pound-feet of torque. Optional is the Vortec 5300 V8, up-rated for 2005 to 300 horsepower and 330 pound-feet of torque.For 2006, the Buick Rainier gets a slight horsepower increase and other minor changes.