Tuesday, April 7, 2015

Why the New Z06 Is the Ultimate Corvette

To really understand the 2015 Chevrolet Corvette Z06, you need a racetrack. With 650 horsepower and an available aero package that generates actual downforce, this is a car that best showcases its talents at extralegal speeds. Which it attains in a major hurry. "It does zero to sixty in three seconds," says Z06 chief engineer Tadge Juechter. "And that's not using launch control or anything." To prove that assertion—and other bombastic Z06 stats, such as its 1.2-g cornering ability—General Motors brought a small fleet of Z06s to Spring Mountain Motorsports Ranch in Nevada, where some of the car's development work was done. In the words of noted poet Bon Scott of AC/DC: "No stop signs, speed limit / Nobody's gonna slow me down."

The quickest Z06s use GM's new eight-speed automatic transmission rather than the seven-speed manual. In a further affront to humanity, the Z06 posts its best lap times with its traction control engaged. GM calls its system Performance Traction Management, and a ride with chassis development engineer Alex MacDonald reveals that PTM requires a recalibration of my throttle-modulating instincts. MacDonald simply flattens the accelerator out of every corner, letting PTM sort out the power delivery. "We have a different philosophy with PTM than Porsche and Ferrari have with their systems," MacDonald says. "They're starting from the perspective that it's a safety net to help you go fast while enjoying your car. We're looking at it as a performance aid—even the best driver is going to go faster with this on than with it off."

That's because even the most sensitive right foot is outmatched by the LT4 engine's 650 horsepower and pound-feet of torque. While the last Z06 was high-revving and naturally aspirated, this one has a 1.7-liter supercharger nestled between its cylinder banks. GM considered turbos, too, but rejected them because the required plumbing would likely force the engine forward. A GM engineer tells me that, all else being equal, this engine would make 740 horsepower with turbos. But GM's logic is sound: This car needs weight over its rear tires more than it needs another 90 horsepower.

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