Pricier Cadillac STS models arrive with a 4.6-liter Northstar V8, producing 320 horses and 315 lb.-ft. of twist. In addition to VVT, both engines employ electronic throttle control to precisely meter power. A five-speed automatic is the only transmission offered for the 2005 Cadillac STS.

Order the V8, and all-wheel-drive is optional; STS V6 models initially make do with rear-drive only. Eventually, however, AWD will become available across the lineup. Under most circumstances the AWD system distributes torque in a 40/60 split favoring the rear. But when traction fades, all four wheels adjust to maximize grip. The AWD hardware works in harmony with StabiliTrak, GM’s electronic stability and traction control system..

We recently drove all three versions of the 2005 Cadillac STS, following a presentation in GM’s Noise, Vibration and Harshness (NVH) testing facility at its proving grounds in Milford, Mich.,, where a vehicle’s quietness is measured in every way imaginable. Getting into the Cadillac STS was easy thanks to wide-opening doors, as well as seats and a steering wheel that accommodate almost all body sizes and driving positions. After engaging the push-button start, we gave the upscale cabin high marks, including its quietness and isolation.