Despite looking like the steel chassis of the base Corvette, the C6 Z06's aluminum frame weighs nearly one-third less. And besides the core-material difference, it features a unique manufacturing process that incorporates MIG and laser welding, as well as self-piercing rivets, while the base Corvette frame is assembled with conventional spot-welding techniques. Additionally, magnesium is used for the engine cradle and some of the other suspension attachment points, further contributing to mass reduction.
On the outside, the Z06 differs from base Corvettes with carbon-fiber panels used for the front fenders, front wheelhouses, hood, and rear fenders. A check of Chevrolet's latest press data shows the car's curb weight at a svelte 3,175 pounds. Interestingly, the base Corvette is listed at 3,208 pounds, a mere 33-pound difference. If that doesn't seem like much of a trade-off for an aluminum chassis and carbon-fiber body panels, keep in mind that the Z06 packs some beefier components, including brake rotors that are about 10 percent larger and a larger rear-axle assembly. It also features a dry-sump-type oiling system, which has a separate reservoir tank and about twice the oil capacity of the base car. So, the low-mass structure elements don't merely cut the weight of the car; they work to offset the weight of the heavier higher-performance elements.
The Corvette ZR1 uses the same aluminum chassis structure as the Z06 and incorporates even more carbon-fiber body parts, including the roof panel, but the there's a weight penalty for the LS9 engine's intercooled supercharger system. The ZR1 tips the scales at 3,333 pounds, but all that extra weight isn't attributable to the blower. It has an even larger rear-differential carrier than the Z06, as well as other heavier-duty--emphasis on heavier--drivetrain components. Then again, with a power-to-weight ratio of 5.22:1, or 1 hp for every 5.22 pounds, the ZR1 can outpace all but a few race-car-derived production vehicles.
In case you hadn't noticed, cars have been getting obscenely heavy in recent years, with much of the excessive poundage coming from dense steel used in crash protection, along with the seemingly dozens of airbag modules and miles of wiring for chassis-control systems. A new Camaro SS with an automatic transmission weighs more than 3,900 pounds, while a family car such as the Buick LaCrosse tips the scales at more than two tons--and we won't even bother listing the tank-like weights of popular crossovers.
That the Corvette has remained unequivocally a lightweight car in this day and age is remarkable. But despite its heritage as a technology leader, particularly in lightweight materials, Corvette engineers are under the same pressure as the rest of the industry to deliver on tougher-than-ever crash standards--and the car isn't about to lose any of those high-tech electronic control systems, either. Maintaining its low-mass credentials, then, will require the continued use of lightweight body panels, but with carbon fiber still considerably more expensive than SMC, it's likely the plastic panels will remain on at least the base models.
As for the chassis, we'd be surprised if separate frames will be justified for base and higher-performance models under the new austerity of post-bankruptcy GM. With luck, that could mean the trickle-down effect will deliver a lighter-weight chassis for the base models. It seems to us that maintaining the base-model coupe's curb weight in the 3,200-pound range will be difficult. But based on the Corvette's track record of continual advancements, particularly over the last 15 years, we wouldn't bet against it.