The 3.6-liter V6 engine generates 254 horsepower, the base V8 produces 320 horsepower, and the supercharged V8 delivers 469, making it the most powerful engine ever produced for a Cadillac. But even the V6 does a more than adequate job of moving its 3,857-pound burden down the road. While the sound of the V6 isn't as robust or viscerally satisfying as that of the V8, it's nothing to be ashamed of either.

The sportiest setup, not counting the monster STS-V, is the V8 with the optional performance handling package. Nudge the shift lever over to the right, into the manu-matic gate, where the selected gear will hold all the way up to redline. Base V8 models now come with the same Hydra-Matic 6L50 six-speed automatic that was exclusive last year to the STS-V. It features a generous 6.04:1 maximum overall ratio for rapid launching off the line, while also providing tall overdrive ratios that decrease engine rpm and reduce noise levels while cruising at highway speeds.

Alternating between the accelerator and brake pedal allows frolicking at extremes heretofore beyond the reach of sedans wearing the wreath and crest. Cadillac's suspension engineers have demonstrated they understand the difference between stiff and firm. Thankfully, all the sound filtering and deadening doesn't keep the V8's throaty exhaust note out of the cabin. Who needs a stereo with these tones to enjoy?

The all-wheel-drive system is a hard package to top, however, complemented by Magnetic Ride Control and the latest generation StabiliTrak, though this adds some weight and isn't available with the handling package. Still, body lean in even the tightest switchbacks is almost non-existent, and mild whoop-de-doos barely give occupants' stomach a flip. Biasing 60 percent of the power to the rear wheels gives the all-wheel-drive STS the sporty dynamics of rear-wheel drive while sending enough power to the front wheels to pull the car through and out of corners with sureness and confidence.

The electronic steering is a delight, its only shortcoming a slight softness on center. The STS tracks well through corners; and turn-in is crisp, especially with the 18-inch, low-profile tires.

The brakes are up to the car's potential, with a firm pedal and a feel that's more linear than not. Cadillac has ratcheted the StabiliTrak back a smidgen from its earlier aggressiveness, and it now waits a bit longer before stepping in. And when it does, it does so less abruptly, too. That's an improvement from a driving enthusiast's point of view because the electronic aids are less intrusive.

All three engines are GM's latest designs with double overhead cams, four valves per cylinder and variable-valve timing. Called VVT, this latter system continuously varies valve operation to generate the most power from the least amount of fuel with the lowest emissions possible. Torque is what most of us experience as power in everyday driving; torque is what gets a car moving in the first place, like when accelerating from an intersection. Recognizing that, Cadillac engineers designed the STS engines to generate lots of torque throughout the rev range for responsive performance at all engine speeds.

The 3.6-liter V6 gets a dual-stage intake manifold that makes available 90 percent of the engine's peak 252 pound-feet of torque from 1900 to 5800 rpm.

The 4.6-liter V8 uses electronic throttle control, sometimes called drive-by-wire, to match the engine's performance to a variety of driver demands, from sedate highway cruising to rambunctious back-road motoring. The V8 generates 315 pound-feet of torque at 4400 rpm.

The STS-V's 4.4-liter supercharged V8 pumps out 439 pound-feet of torque, with 90 percent of it available in a wide sweep from 2200 to 6000 rpm. This enormous thrust is delivered smoothly through the six-speed automatic transmission. However, the heavy-duty upgrades found in virtually every dynamic element of V-model car, including harder-riding lower-profile tires, make the STS-V only suitable for those willing to sacrifice some comfort in return for jetting from 0 to 60 mph in less than 5 seconds. There's also the STS-V's $2,100 gas guzzle tax to consider.