Body panels provide a better opportunity for weight savings. Much of the C6’s body is made of sheet molding compound, which contains heavy silicon. Switching to carbon-fiber panels for the base models would be too costly, but there are several emerging composites, including Kevlar/carbon-fiber and Kevlar/aluminum that could lower weight without seriously raising cost.
A mid-engine C7 would get a version of GM’s upcoming “high-feature” V-8, expected to be an efficient, direct-injection 5.0-liter-plus gas engine with quad cams and four valves per cylinder and due to launch in 2009 to replace the Northstar V-8.
Building only the mid-engine C7 has its advantages. GM could sell the car at lower volume than last year’s 36,000 C6s and fill in some of the loss with added sales overseas. With U. S. sales approximately halved, Corvette would have less effect on GM’s CAFE numbers.
Building a powerful, high-tech mid-engine car also could prove costlier than expected, as Ford discovered with its low-volume, short-run GT. The profit margin might not be as good as it looks.
The C6’s greatest shortcoming is that it doesn’t feel as light on its feet as it really is or as rigid and precise as it should be. Memo, C7 engineering team: Just go and drive a new Jaguar XKR coupe. You’ll see what we’re talking about. Yes, a current Z06 can complete the Motor Trend figure eight in 24.9 seconds at 0.79 g average, versus 25.8 seconds at 0.75 g for a 911 Carrera S. But the feel and feedback could be much better, especially through the steering. And, as we found in our giant handling test (June 2007), the stiff sidewall run-flat tires make the Z06 too tail-happy in high-speed turns. A stiffer chassis would help steering feel and fine-tuning of the suspension.
While the C6’s carbon-fiber transverse leaf springs are light and packaged well, under some conditions they make the rearend behave a bit like a rigid axle. Aftermarket tuners have scrapped them in C5s and C6s for coil-spring conversions, so it’d be easy to do in a production C7. The C6 has aluminum control arms front and rear, but reductions in unsprung weight would help further.
A new C7 means a new Cadillac XLR, as the two cars share the same frame and other key components. The current Cadillac XLR is a triumph of ambition over reality. While the basics are good—the dramatic styling, the smooth and punchy supercharged Northstar in the V-series version, reasonably well-mannered chassis—the details are not.
Cadillac needs a $100,000 sports car to act as a halo for the brand. But it must look, touch, smell, and feel like a car worth $100 grand. And that doesn’t make a case for a mid-engine Corvette, so Cadillac can have a mid-engine XLR: As delicious as the Detroit show-stopping mid-engine Cien concept was, Cadillac’s benchmark for a new XLR isn’t Audi’s R8, but the evergreen Mercedes-Benz SL.
If GM wants to do a mid-engine supercar, make it a limited-volume Cadillac positioned above the XLR. But the money would be far more wisely spent developing a large rear drive Caddy sedan to compete with the Mercedes-Benz S-Class first.
