Chevrolet Corvette Z06 / Ford Shelby GT500 Cobra

Business Jet Traveler » December 2007
The Chevrolet Corvette Z06 and the Ford Shelby GT500 Cobra
Saturday, December 1, 2007 - 4:00am

A neighbor of mine counts a late-model six-speed Corvette coupe among his household's half dozen cars and nine motorcycles. When I remarked to him that the Shelby GT500 seemed to be attracting more come-hither glances from women than the Z06, he didn't miss a beat: "You been cruising around trailer parks?" The loyalty these cars generate is as fierce now as it was back in the good old days.

The good old days? Bah, humbug. Blinkered by warm and fuzzy memories, it's easy to inflate recollections of how good these two cars were in their (and our) youth. They were good for their time 40 years ago, but the Corvette and the Mustang have never been better than they are today, in every respect except one: auction prices of concours classics are sky high, driven by that same blind and powerful emotion called nostalgia.



Regardless, factory-fresh cars that are far more capable are in Chevy and Ford showrooms right now. How much better are today's cars? In 1967, the 427 Corvette Sting Ray's four-speed stick and 435 hp could propel its 3,340 pounds from zero to 60 mph in 5.6 seconds, and the GT500's four-speed stick and 355 hp could launch its 3,360 pounds from a standstill to 60 in 6.2 seconds. The low ends of the mpg range were 9.0 for the Vette and 7.6 for the Shelby. They're all dull numbers compared with those for the new cars-new cars equipped with pollution controls for far cleaner exhaust emissions.



The old Vette had four disc brakes, but power assist was optional; power assist was a "mandatory option" on the Shelby, and on the back you could have any sort of brakes as long as they were drums. Airbags? Anti-lock? Traction control? Xenon lights? Nope-and that's probably part of the appeal of the old cars these days. In 1967, the 427 Sting Ray started at $4,764, the GT500 at $4,460.



I strapped into the two '07 models with no preconceptions or brand bias, and after putting about 1,200 miles on the cars in one week, I could not decide between the two; regardless of specification numbers, whichever car I was driving at the time seemed to be the better. My cop-out conclusion was that, if I had room in the garage for only one, I'd build onto the garage to avoid choosing. The two machines are surprisingly different (particularly because of weight and seating), despite the surface similarity in power and mission.



The Corvette's clutch is lighter and, with no breathing assistance between the driver's right foot and the intake, its accelerator response is more immediate; the Cobra is more comfortable as a conveyance, not only because the driver sits higher and more upright but because engine and transmission heat is kept out of the cockpit more effectively. Coins and keys left in the map compartment/armrest that straddles the Z06's transmission tunnel are too hot to handle after a spirited 60-mile drive; the temperature there reached 141 degrees F, so the air conditioning is not just for hot summer days.



Both cars have the deep, menacing growl of an American V8, but the Cobra's crescendo is accompanied by the rasp of forced respiration as the supercharger stuffs air into the inferno. Sixty mph in the Z06 coincides with the 7000-rpm redline in first gear, so the Chevy can lunge to that tell-all benchmark without shifting. In first gear, the Cobra redlines at 50 mph. The Corvette has the edge in the brutality of its assault on the speedometer but, despite the disparity in the 0-60 numbers, neither car will disappoint on acceleration.



When you're loafing along at 75 mph in sixth gear, the Corvette's engine spins at just 1600 rpm, the Cobra's at 2000 rpm. Both cars have plenty of torque for accelerating at lower rpms, but the power of the Corvette's long-legged gait in the upper gears is spectacular. From 2000 rpm in fifth at 63 mph, the car pulls like a twinjet to 80 mph with a gain of just 600 rpm. It is impressive to feel so much shove in the back from so little movement of the tach needle.



In deference to gas mileage, both vehicles have features that seem out of place on fire-breathing sports cars. They relate to gear shifting, and they're both defeatable. If the Corvette's brain deems the driver's demand for acceleration in first gear to be half-hearted, it blocks second and third gears, forcing said driver to upshift from first directly to fourth. Every time it happened, I thought I'd made a hash of a shift, but it was actually the car that had botched it. My neighbor disabled the feature on his Corvette, and I'd hobble the Cobra's upshift light, too.



The Corvette has the edge in the sophistication of its engineering. The seven-liter engine is kept lubricated under heavy Gs by an eight-quart dry-sump oil system, and it has titanium valves and con rods. Significantly, the Z06 does not incur a federal government gas-guzzler penalty, thanks to its tall gearing in sixth and, no doubt to some degree, to that first-to-fourth shift hijacker. (The GT500 sticker carries a $1,300 gas-guzzler levy.) The Z06's weight loss stems largely from the aluminum frame and the magnesium roof structure and engine cradle-its aluminum body structure weighs only 278 pounds, 136 pounds less than the regular Corvette coupe's. Stopping is as impressive as starting, thanks to six-piston front calipers, each piston pushing its own pad, and 14-inch vented and cross-drilled rotors in the front (13.4 inches in the back). Four-wheel independent suspension and a head-up display with cornering G meter round out the engineering advantages of the Chevy.



The GT500 has independent MacPherson struts in the front and a three-link solid axle with coil springs and 24-mm stabilizer in the back, the whole assembly tuned by Ford's SVT people for a ride that is comfortable for everyday motoring and capable of fun at the track but lagging the Corvette's more track-happy suspension. The Ford does not lack stopping power, thanks to Brembo 14-inch rotors in the front grabbed by four-piston calipers. The GT500 takes the heavy-duty 5.4-liter V8 with cast-iron block and combines it with the Ford GT's cast-aluminum four-valve cylinder heads, and new camshafts and valvetrain. In 1968, the seven-liter Shelby GT produced only 360 hp and 420 lb-ft with no anti-pollution equipment.



 Forced to choose between the two, I'd buy the Z06 if I intended to take the car to the track; for nothing more than driving on public roads, I'd be just as happy with the GT500, and spend about $34,000 less.

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