Besides an option for AWD on the V6 trim and a few new exterior colors, not too much changed for the luxury sedan in 2006. The STS comes in two trims: V6 and V8. The V6 uses a 3.6 L, 255 hp V6 powertrain with 5 speed automatic transmission while the V8 uses a 4.6 L, 320 hp V8 engine. Both trims have 4 doors and seat 5. On average, expect to get 16 mpg in the city and 24 on the highway. Standard features include air conditioning, power windows, power door locks, power/leather seats, cd player, ABS brakes, traction control, and stability control. Options include sunroof and navigation system. You and your passengers will have 103 cubic feet of room to stretch and 13.8 cubic feet in the trunk. Overall, drivers have a lot to like about the 2006 Cadillac STS. The optional AWD in the V6 trim, optional Bose system in the V8, and low price for a full-size luxury sedan make the STS particularly appealing. On the other hand, reviewers can tell that this domestic vehicle doesn't quite measure up to its foreign competition when it comes to interior materials. The 2006 Cadillac STS gets a solid grade from its drivers as a capable successor to the acclaimed Seville.