Introduced last year in the CTS and the SRX, the 255-horsepower 3.6-liter V-6 in the base STS is good for 252 pound-feet of torque, and, we are glad to report, it's no slug. Both the six and the V-8 profit from variable valve timing, the six revving to an un-GM-like 6700 rpm, while the 4.6-liter eight spins happily to 6450 rpm, making 320 horsepower and 315 pound-feet of torque.
One of the benefits of the rear-wheel-drive chassis is that, unlike some previous front-wheel-drive Sevilles, which suffered from prodigious torque steer, the traction and stability-controlled rear-wheel-drive STS always puts the power down smoothly and never sends you darting for the guardrail. All-wheel drive makes nasty surprises even less likely.
On the road, the new DOHC engines don't match the Germans for aural excitement and don't achieve the cream-coated delivery of the Japanese. But they lack neither smoothness nor power, the V-8 propelling the STS from 0 to 60 mph in 6.9 seconds.
Unexpectedly, we found ourselves preferring the six-cylinder car (with Magnetic Ride Control), which felt more enthusiastic on the many tight and sweeping curves of California's coastal Highway 1. It's an extremely likable car, but in truth, all five of the STS models we drove-six, eight, all-wheel-drive, up- and down-level suspensions-were superior automobiles, though none possessed the joie de vivre of a BMW or a Mercedes. The STS is no back-road stormer, it's more of a high-speed interstate sweeper. But if it's no turn-in monster, it's no barge, either. It is a compelling proposition overall.
If the STS faces a problem, it is simply this. Far from posing a challenge for cross-shopping 7-series intenders, as Cadillac suggests, the STS will have to slug it out with cheaper cars, such as the excellent Chrysler 300 and the very fine CTS, which resides below it in Cadillac's hierarchy yet shares the same architecture and V-6 engine, provides imperceptibly less passenger accommodation, and is available for considerably less money.
If we're still thinking German here, the STS begs the question of what comes next. If Cadillac really wants to go upscale, it's going to have to bring on a true 7-series/S-class fighter. With the CTS and the STS, the games-and the names-have just begun.