V for Vendetta indeed

This Cadillac has five-point harnesses. Its hand-stitched leather dash has a bunch of non-production toggles and buttons for stuff like the fire extinguisher. Also odd is that there's a guy in the driver's seat wearing a helmet. This would be John Heinricy, the man who has taken many a GM car to its limit on the Nürburgring Nordschleife, and who has pushed this very Cadillac CTS-V to a time of 7:59:32 on that 13.9-mile track. Today, the venue is a bit less auspicious but no less important: Heinricy is about to demonstrate the CTS-V on a couple of hot laps around GM's newest test track at its Milford Proving Ground. This handling loop was built four years ago at the behest of one Robert A. Lutz, and it is a tangle of some seriously demanding turns, many of them inspired by that little country circuit in Germany. As with the Nürburgring, there is a Karussell and a downhill double-right-hander like Pflanzgarten. Hence, the place's nickname: The Lutzring. It's a wonder that a company as large and as powerful as GM hasn't had something like this until now, but it also explains why, until quite recently, so many of GM's cars handled like drunken rhinos.

I'm just riding along today, not driving, but the point of this exercise is to get a small, passenger-seat taste of the new CTS-V as it goes through its final exam. The V is here for a 24-hour pounding at racetrack speeds, testing suspension robustness, engine-and-brake cooling, tire wear, and the overall durability implicit in a sport sedan of this caliber.

For a little context, here's the caliber we're talking about: 556 horsepower; 551 lb-ft of torque; 0-60 in 3.9 seconds; quarter-mile in 12.0 seconds at 118 mph; top speed of 191 mph (with the manual transmission). GM is claiming that this is the fastest production sedan in the world; it made its epic Nordschleife pass on stock PS2 tires, in a car equipped with an automatic transmission (top speed: 175 mph).

Indeed, it's kind of amazing how little — besides the obvious powertrain changes — it took GM to get the stock CTS there. It's got new brakes, magnetic dampers, and a revised rear axle assembly; but the control arms, the steering rack, and even the anti-roll bar bushings are the same. The goal here was to retain the easy-driving character of the stock sedan, but to add a layer of mind-bending performance to the proceedings. From what I can tell as a passenger, the results are staggeringly successful: The car feels imperturbable, both from the standpoint of chassis stability and power delivery.

The V gets its stability from GM's second-generation Magnetic Ride Control (MRC) dampers. Like the system that made its debut in the current STS, MRC uses a magnetic field to get ferrous particles inside the damper to line up and provide resistance in proportion to the field applied. Now, however, the magnetic fluid reacts even faster than before (the old system was already the quickest-responding damper technology out there), and makes even better use of the accelerometer data to take an anticipatory, rather than a reactive, approach to cornering and ride control.

The car's driveline characteristics have been cleaned up, too. One major flaw with the old CTS-V was its dominant axle hop. Not so surprising, really: Anytime you get a lot of horsepower together with a rear-wheel-drive, limited-slip-equipped, independently suspended chassis, there will be some wind-up (although not, it must be said, as much as in the previous CTS-V). Other carmakers pull all kinds of torque-mitigating tricks to eliminate axle tramp, but GM's performance division got to the root of the problem. Besides using a cast-iron diff casing, upsizing the propshaft, and reducing driveline lash with CV joints, GM also found a way to defeat the phenomenon itself. A slipping wheel will wind up its half shaft until the wheel hooks up, at which point it sends that force back through the shaft to the opposite side, setting up a spring-like effect through the axle. GM unbalanced the half shafts (the left side's diameter is 55 mm, the right side's is 35 mm) to decouple the forces and eliminate the spring effect. The result is a car that launches like the space shuttle. Power has nowhere to go but down to the ground.

Obviously, the car needed more robust brakes, but GM also thought hard about how to keep them from adding more unsprung mass. The 380-mm front/373-mm rear Brembo discs are co-cast, meaning the aluminum hat is cast in, rather than bolted onto, the steel rotors (they are clamped by six-piston calipers at the front, and four-piston calipers at the rear). This saves about a pound at each corner, and helps quell rotational inertia. Other places GM saved weight: Forged alloy wheels, reduced NVH insulation, and lower-mass tires, all of which help to keep weight within about 200 pounds of the base CTS.

But what's a little weight when you've got a 556-hp V-8 underhood? This is the supercharged LSA small-block — it's essentially a lower-compression, 6.2-liter LS3 from the Corvette with a 1.9-liter-displacement version of the blower you've no doubt salivated over in the ZR1. It uses a rotor design with four lobes, a single-brick air-to-water intercooler, and it will simply not give up. Dave Mikels, the CTS-V's powertrain integration engineer, says, "In most supercharged cars, you have to let them rest between runs or you'll see horsepower drop off. That doesn't happen here." Mikels demonstrates this on the road where he does his performance testing, dropping the clutch for yet another quarter-mile sprint. As he goes through the gears, I see little red lights crawl up the tachometer, letting him know that the soft-limiter is about to intervene. "The torque curve's so flat," he says over the low rumble of the exhaust, "that we had to let people know when to shift."

Back at the Lutzring, Heinricy slaps the car into drive and we're off through the first turn, a very technical and slow right-hander. Then he boots it and a huge wave of power sends the car over three uphill blind sweepers. There is a ton of lateral grip — the tires don't even squeal through here — and Heinricy is on the power before you or I would ever dream of tapping the gas pedal. The track sends us through its version of the Karussell, putting full compression into the suspension and unloading it completely in the corner exit. I've been in other cars through here, and my helmet inevitably bangs up against the headliner when the bowl empties out. Not in the CTS-V. The car stays controlled and fluid even as it gets subjected to physical extremes. I, too, remain demonstrably fluid, if not exactly controlled.

A fast left-hander comes up and Heinricy is adjusting the car's cornering attitude with the throttle. The CTS-V is just dancing through here, and it's easy to see how he could have turned eight-minute 'Ring laps in it all day. He doesn't appear to be working too hard. Some of this might be his incredible skill, but a lot of it is undoubtedly the car. It never gets squirrelly or bent out of shape, even when it's drifting ever so slightly. Somehow, in spite of all its earth-reversing power, it exacts no price for its performance (it's not even that expensive; it goes on sale this fall at an estimated $58,000). The V is a car you could run for 24 hours straight without complaint, from you or it. On the road or on the track the CTS-V remains cool, calm, and collected. It remains a Cadillac