Tuesday, August 14, 2007

Chevrolet Corvette Z06


M wants the world to know that it can take on the best of Europe with the new 505-hp Z06, the fastest Corvette the company has ever produced. To make that point, GM held the first press drive of this American sports car in Europe.

The three-day tour began in Germany, headed west to Belgium, and then southwest for Paris. Along the way we did a handful of laps at the Nürburgring's Formula 1 track, a 3.2-mile course that's next to the famous 12.9-mile Nordschleife course, and at Spa, a 4.3-mile road course in Belgium that has the hairiest downhill-uphill series of three wicked turns we've ever sweated through. That section, called Eau Rouge, provided the biggest thrills of what was basically an uneventful tour. Europeans gawked at the car and seemed to applaud it. They likely were unaware that they were witnessing the arrival of a car that exposes the majority of European sports cars for what they are: overpriced, underperforming snobs.

The Z06 starts at $65,800. It is the most powerful and expensive model in the Vette lineup and, interestingly, the lightest. Usually, the best-performing car in any model lineup is the beefiest, because adding horsepower generally means fortifying other parts of the car to withstand the strain caused by big power.

The Z06's expanded power comes from a new pushrod 7.0-liter V-8 engine. Except for the titanium connecting rods and intake valves, there's nothing in this engine's parts list to suggest that it's a monster motor. The genius here is in the details, with careful attention paid to maximum airflow and valvetrain weight and stiffness. The result is a big engine that revs like a small one to 7000 rpm with a 6300-rpm horsepower peak. The torque curve is wide and flat with more than 400 pound-feet available between 2400 and 6400 rpm.

To handle an engine that could twist a maple tree like a washrag, Chevy beefed up the rear axle, the six-speed manual transmission, and the clutch, and installed wider wheels and larger brakes. The idea, according to assistant chief engineer Tadge Juechter, was to create a robust platform that could deal with the stresses and heat of the big motor. To that end, the team also added coolers for every fluid except brake fluid and enlarged the radiator. To maintain oil pressure during sustained high-g cornering maneuvers, they also installed a dry-sump oil system on the engine. Engine oil is usually carried in a deep pan that hangs on the bottom of the engine, but a dry-sump system uses a shallow pan and an external oil reservoir. Oil capacity is eight quarts for the Z06 versus 5.5 for the base car.

All the new bits added about 100 pounds to the base 3288-pound, 400-hp Vette, a figure that wouldn't burden the Z06's power, which had been increased by 105 horses. But to Chevy's credit, the team trimmed fat like the best Hollywood plastic surgeon.

The headliner in the weight-loss program is the aluminum frame that weighs 136 pounds, which works out to a third less than the regular Vette's heavier but stronger steel unit. To retain chassis rigidity, the Z06 eschews the removable roof for a fixed cast-magnesium structure and another magnesium piece for the engine cradle.

Weight was also shed by using carbon-fiber floorboards and front fenders and liners. The end result is a "mosaic of materials," says Juechter. When all was said and done to the Z06, it weighed in at 3147 pounds, or 141 less than the base Vette. To put that in perspective, Ferrari's all-aluminum F430 weighs 3380 pounds, and Porsche's carbon-fiber $446,000 Carrera GT weighs 3146 pounds.

0510_vettez06_rear.jpgAs little as the Z06 weighs, it does not feel like a light, nimble car. To accommodate the wider rear tires (325/30ZR-19s versus stock 285/35ZR-19s), the Z06's tail bulges an extra 3.3 inches for a 75.9-inch width; the car fills the width of a typically narrow European back road.

By threading carefully through the curves, we had no problem stretching the Vette's legs on the autobahn as we left the Nürburgring. Although we never got close to the car's claimed 198-mph top speed, 150 mph was a breeze. The Z06 has some aero tweaks, such as a deeper front spoiler and a small rear spoiler, that help keep the car planted as the rushing air tries to lift it off the ground.

If we hadn't missed an autobahn exit, we'd have made the 85-mile trip to Spa in record time. Spa is a track we've all seen on TV on the Formula 1 tour, but the tube does not do this circuit justice. The signature section is called Eau Rouge. It starts with a steep downhill straight that's bordered by the pit wall on one side and an Armco barrier on the other. At the bottom of the hill, the course takes a quick left, then immediately bends back to the right as it goes abruptly uphill. At the top of the hill the course shifts back to the left. It is a fast section that's taken at over 100 mph in the Z06, and one can't help getting that sweaty-palm feeling simply watching somebody fly through it.

The rest of the course is filled with fast high-speed sweepers with plenty of elevation changes and a plethora of unfriendly-looking walls, barriers, and trees to get up close and personal with should one go off . The track was built in the early 1920s, when race drivers had a short life expectancy and seatbelts were a future invention.

And remember, we were about to drive this course in a car with a power-to-weight ratio that's better than a Ford GT's (6.2 pounds per horsepower versus 6.4), so obtaining speed would not be a problem. Summoning courage, however, was.

0510_vettez06_left.jpgWe went for a ride with Corvette test driver Jim Mero to learn the course. Heading downhill to Eau Rouge, he accelerated into fourth gear, or about 130 mph. At the bottom of the hill he flicked the car left, then right, and headed uphill and arced back left as he crested. All this in the blink of an eye. The speed never dropped below 110 mph.

We were a little slower through Eau Rouge, but we're not pinning that on the car. The Z06 is very well balanced. It won't do anything that will surprise the driver. Drivers can reliably predict which end will slide based on how the car has been set up to take the corner.

Eventually, we got comfortable. As benign as the Corvette handles, the chassis still moves around and takes some getting used to. Some cars, like the Porsche 911, provide an instant confident feeling that the Z06 does not impart. It's tough to put your finger on exactly why that is. The Z06 corners flatly, and it breaks away in a smooth, easily controlled manner, but it takes some time to get confident with its behavior. The steering is a tad numb, even though we didn't detect any free play or slop.

0510_vettez06_seat.jpgAfter two laps we lined up for Eau Rouge, determined to duplicate Mero's smooth run, and kept the throttle pinned as we neared the bottom of the hill. We hit the dip, flicked left, then right, and headed back uphill. Somewhere in the sequence, we erred—probably lifting off the gas when we shouldn't have. It's hard to say exactly what happened, but the car got squirrelly. We weren't frightened. Terrified is a better word. In the middle of this bad moment, the Z06's stability-control system kicked in and kept us on track.

Yes, the Z06 has a stability-control system with a competition mode that allows enough leeway to let you slide the car, but it will intervene in a dramatic slide. We'd wisely left it on.

That system is part of the Z06's strange dichotomy. On one hand, it's a perfectly reasonable street car. It's easy to get into and out of, there's a 22-cubic-foot luggage compartment, the view out is expansive in all directions, the ride is reasonably plush, and except for some tire noise from the run-flat Goodyears, it's a comfortable highway cruiser. We only found a few annoyances—a transmission tunnel that gets toasty and some gear rattle when we lugged the engine. You could drive this car every day.

0510_vettez06_interior.jpgBut by almost every performance standard, the Z06 is a supercar. A few days after our trip, we took a Z06 to GM's Milford proving ground and tested it. It ripped to 60 mph in only 3.6 seconds, hit 100 in 7.9, and 150 in 17.5. That's on par with or better than the performance of the $153,345 Ford GT (and good luck getting that price) and $180,785 Ferrari F430. Likewise, the brakes are terrific, bringing the Vette to a standstill from 70 mph in only 162 feet. And it pulled 0.98 g on the skidpad. Spending double the Z06's price does not guarantee you'll have a car that can beat it.

When you experience this thrilling car and are aware of the Corvette's string of Le Mans victories (four class wins in five tries), it seems reasonable to say that we're in the golden age of the Corvette.

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