Car and Driver: 2005 Chevrolet Corvette z51
08-31-2004, 02:05 PM
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Car and Driver: 2005 Chevrolet Corvette z51
In a world of disappointment, nothin? but grins.
BY LARRY WEBSTER
September 2004
So, do you still think it's a C5 and 11/16ths?" asked Corvette assistant chief engineer Tadge Juechter in a half-joking, half-serious tone. We had just spent two days driving the newest Corvette the so-called C6 around the hills of southern Virginia and at Virginia International Raceway, and Juechter was repeating, almost verbatim, a headline we'd placed on a preview story of the car. It had probably ticked him off then, but it wasn't showing now.
Although most new-generation Corvettes have been a dramatic departure from the previous version, the C6 Corvette is not a clean-sheet design. And so what? It only proves what we already knew: With the C5, Chevy got most of it right. Even in its last year of production, 2004 after an eight-year run the C5 Corvette was judged a 10 Best Car by us. Corvette chief engineer Dave Hill alluded to that point when he said, "We're not inventing we're perfecting." And perfect they did, making a mix of dramatic and detail changes to the C5 and creating a Corvette that's better in every way.
It's now a tidier package?shrunk by 5.1 inches and riding on a wheelbase 1.2 inches longer. The wide rear flanks have been trimmed an inch. The result is quite dramatic. The Corvette has shed its extravagant proportions for a body that's much leaner and looks more aggressive. The body is still fiberglass, but the design team spent hours in a wind tunnel searching for ways to reduce both drag and wind noise.
Then there's the engine. The basics are quite sweet: A 2.6-millimeter increase of the bore bumped displacement from 5.7 to 6.0 liters. It has 50 more horsepower and 25 more pound-feet of torque (40 more pound-feet in automatics), elevating the output to 400 in both departments, with the redline increasing by 500 clicks to 6500 rpm, the same limit as in the old Z06. The gear linkage of the six-speed manual transmission has been updated for shorter throws and a more precise feel.
The suspension got a thorough redo, too. With new shock absorbers, the length of travel is increased by 0.3 inch in front and 0.8 inch in back. The front caster angle is up one degree for better straight-line stability, the anti-roll-bar mounts are stiffer, the bushings have been revised, and the spring and damping rates have been modified.
The wheels grew an inch in diameter, with 18-inchers up front and 19s in back. The run-flat tires remain, but Juechter says Goodyear softened the sidewalls to improve ride quality.
We had two major complaints about the old car: The drab, monochromatic interior had a cheapness you wouldn't accept in a Cavalier, and the seats felt flat and flimsy. Both are gone. The new seats feature a longer bottom cushion, have supportive bolsters, and hold the driver in place far better than the old ones. The dash was redesigned and uses a combination of textured plastic, vinyl, and aluminum that looks and feels like high-quality stuff. And as before, The Vette is generously roomy inside.
For the first time, the Corvette is available with such luxuries as a navigation system and seat heaters. Keyless entry and start-up with a pushbutton are standard. Electric door latches have been added, so the odd-looking interior door handle is replaced by a simple button. The interior looks and works better, with only one ergonomic mistake: The buttons used to page through the trip computer and a series of various gauges are mounted on the outer rim of the gauge cluster where they are blocked completely from view by the steering wheel.
Nothing in our test car rattled or squeaked?a testament to the C6's rigid frame, changes to which were minimal, other than having its ends clipped. Hill says the frame is only fractionally stiffer and lighter than the old one. More significant, a second transmission mount has been added, and the engine was moved forward a hair (0.07 inch) to make room for a larger clutch that the team thinks will be necessary for the next, higher-powered Z06, due late next year with a rumored 500 horsepower.
Corvette coupes (they all have a removable roof section) and convertibles come in three forms: base, F55 (add about $1700) with adjustable magnetorheological shocks, and Z51. The Z51 package, which will cost about $1500, includes a stiffer suspension, tires that offer better dry-road grip, larger brakes, a six-speed manual with shorter ratios, and a transmission-oil cooler. Expecting a Z51 to be the best performer, that's naturally what we tested.
Before we get to the numbers, a word about ride quality. It's impressively smooth. The suspension communicates the contours of the road and filters out the harshness. Frost heaves cutting across entrance ramps that used to make the hind end jittery are now soaked up nicely. There's a resilience to the suspension that reminds us of BMW's 3-series.
The tires grip fervently, generating 0.98 g on the skidpad. That matches the best of the three Z06s we've tested and vastly surpasses the 0.90 g that our grippiest non-Z06 C5 generated. The C6 has the same balanced feel as the old, with a willingness to slide either end depending on how you play with the pedals. Now, however, it sticks to broken pavement better and is much more accommodating over midcorner bumps. The brakes, too, are wonderful, with good modulation, zero fade, and a stopping distance from 70 mph to a standstill in 166 feet, about the same as the previous car.
The stability-control system has a button that either shuts it off or selects a competition mode that allows more slip before intervening than the fully active mode. It is perhaps the best version of stability control we've ever sampled because it offers an appreciated safety net and yet permits 0.96 g on the skidpad in both fully active and competition modes.
With the system off, the Vette galloped to 60 mph in 4.3 seconds and through the quarter-mile in 12.7 seconds at 113 mph. The C5s we've tested have averaged 4.9 to 60 and 13.4 at 108 in the quarter, and the quickest Z06 [C/D , December 2001] ran 4.0 and 12.4 at 116.
Of course, the C6's more powerful engine is partly why it outruns the C5, but so is its weight. Our test car weighed a minimalist 3224 pounds. That's lighter?by about 60 pounds?than any C5 coupe we've tested. Moreover, the C6 is only 78 pounds heavier than the carbon-fiber $448,400 Porsche Carrera GT. And this mass efficiency was achieved even though the C6 has more features and more sound deadening to quiet the interior. Although our sound-level meter didn't hear a noticeable improvement, back-to-back comparison drives with a 2004 Z06 suggest this new Corvette is much quieter.
One of the goals, Hill says, was to increase performance while improving the Corvette's refinement. This is now a car with an amazingly wide range of capabilities. Around VIR, we drove a Z51 for maybe 20 laps as if it were someone else's, but its performance was so strong that we never tapped the limit of its potential. And it didn't show a single sign that the hot laps were detrimental. It's the perfect everything sports car: fast enough to keep you interested during a day of lapping and refined and comfortable enough to make the slog home, or the daily commute, a relaxing experience.
But even though the C6 is better in every way, Chevy says it will cost roughly $1000 less than the C5. The base car will start at about $43,500 and comes standard with the six-speed manual, which was a $915 option. Our test car had the $1500 Z51 package, a head-up display, heated seats, and OnStar and would probably run about $47,000.
Take any sports car within 20 grand of the Corvette's sticker, and the Vette will flat smoke it. We think the Corvette may also prove a match for the upcoming $70,065 321-hp Porsche 911 and could very possibly outgun the $79,865 350-hp 911S. Oh, and don't bet against the Vette's earning another 10Best spot.
------
The Small-Block Keeps Chugging Along
There was no single trick that produced another 50 horsepower for this pushrod 16-valve aluminum V-8 but rather a series of detail changes.
Dubbed the LS2, the new engine has a larger bore than the LS1 (101.6 millimeters versus 99.0) and a higher compression ratio (10.9:1 versus 10.1:1). Intake airflow was improved by 15 percent, exhaust flow by 20 percent, the valve lift on the cam was raised, and some internal modifications were made to reduce pumping losses. Horsepower is now 400 at 6000 rpm (the C5's was 350 at 5200), and torque is 400 pound-feet at 4400 (the C5's was 375 at 4000 in six-speed manual cars, 360 in automatics).
About 15 pounds were trimmed from the engine's weight by using a thinner-walled exhaust manifold, a smaller water pump, and an aluminum oil pan that requires one quart less of oil. The pan contains a series of compartments and baffles to keep the pickup bathed in oil during high-g maneuvers?even with less total oil capacity.
The engine continues the tradition of alluring low-end thrust and the instant throttle response that we love in a small-block. The Z51's sixth gear is about 14 percent shorter than the C5's, which helps top-gear grunt. The car takes 9.8 seconds to accelerate from 30 to 50 mph in sixth gear and 9.0 seconds to go from 50 to 70. The best C5 needed 11.6 and 11.7 seconds, respectively.
And we're still impressed with how effectively the relatively simple pushrod engine offers power and efficiency, demonstrated by the fact that the C6 makes 400 horsepower and doesn't get stuck with a gas-guzzler tax.
Aero Tricks
To get a sense of just how fanatical the Vette guys are about sweating the details, spend a few minutes with Kirk Bennion, the C6's former lead exterior designer (he's now the design manager). Bennion helped tweak the C6's new shape. It may not look as smooth as the C5, but the C6 actually cuts through the air better and has a Cd of 0.28 versus the old car's 0.29.
Decreasing drag wasn't easy, especially considering that the C6's shorter body and wider rear tires increased drag. With the help of a wind tunnel, Bennion says the team tweaked the airflow in a lot of small areas for an overall improvement.
Take, for example, the area below the front fascia. There's a black air dam that runs across the bottom of the nose. Its job is to reduce the amount of air that flows under the car. It's roughly three-and-a-half inches off the road, and this will sound funny, but designers know it will scrape the surface when, for example, dipping into a parking lot. It's meant to hit the ground, though, and it won't be damaged when it does. (The C5 had a similar piece, but now Hill says the C6's makes less noise when it contacts the road.) The devil's in the details?there are curves at each end of the air dam. The radius of these curves was carefully designed so that air coming off the dam stays close to the body to minimize drag-inducing turbulence.
The engineers also found a high-pressure area just ahead of the air dam that is used to supply air to the front brake ducts. On the C5, the ducts inhaled air from the front of the car.
Chevy claims the C6's top speed is 186 mph. We weren't provided with enough runway to test that claim, but we did see 178, and the car was very stable. Also, the window sealing has been improved, so rather than bow out at 150 and make a deafening roar as the C5's did, the C6's windows stayed put.
As for abandoning a Corvette trademark?pop-up headlights?for fixed units, the team reports that the new lights weigh less, don't take up as much space as the old ones, and don't increase drag when they're turned on. It seems that when it comes to performance, nothing is sacred.
A power-operated softtop makes its debut.
We never had any gripes about the C5's manual softtop. Even though it didn't go down automatically, it was easy to use, and we appreciated the weight saving realized by skipping on the power mechanisms. Now, the convertible has an optional power-operated top, expected to cost about $2000. All the driver has to do is unlock a single header latch and press a button. Automatically, the top folds behind the seats, and a neat, hard boot lowers to conceal it?in about 20 seconds. The power top weighs just 18 pounds and has a soft liner. During our brief drive, it did a reasonable job of keeping out the noise.
All convertibles now have a rear bulkhead that separates the passenger compartment from the roomy trunk, which offers 11 cubic feet of space, or five with the top down. In previous Vettes, the trunk could be accessed from the cabin, at the price of a lot of noise created in that hollow chamber, so it has been sealed up.
With the top down, wind buffeting is fairly well subdued. A wind blocker is in the works. We were surprised to discover just how much we prefer the Corvette convertible to the $76,200 Cadillac XLR. They're built on the same platform, but the Vette is roomier for lanky folks, and its pushrod 400-hp V-8 is 80 up on the Caddy's 320-hp DOHC unit. And, for the first time, the Z51 Performance package is available on the convertible. Who would pass that up for an XLR?
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THE VERDICT
Highs: More powerful engine, attractive interior, comfortable ride, immense grip, fantastic price, supportive seats, balanced handling, short-throw shifter . . . we'll stop there.
Lows: The various electronic features?keyless start, auto door locks, electric door latches?can be more annoying than useful.
The Verdict: Hill and company have given us more of what we liked, fixed what we didn't. A five-star ride.
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COUNTERPOINT
TONY QUIROGA
Nearly everything that bothered me about the last Corvette has been addressed in this incarnation. Where the old car felt like an ill-fitting superhero costume, the new car feels tailored, taut, and less ridiculous. A shorter shifter and lighter clutch-pedal effort make gearchanges a pleasure. The ride is better, too?more compliant and painless. The changes all work in concert to make for a better Vette and a happier driver. But nothing is perfect. The interior is a great improvement over the old in materials and design, but it's a bit uninspired. And there's that lingering odor of resin inside. If that's all I can find to complain about, this Vette is a success.
STEVE SPENCE
Details, details. Good: The shifter throws have been shortened. The tailpipe music is brand-new (like an NSX with attitude). At last, new dash knobs and switches. Not good: Who needs keys that don't work like keys? I would never opt for the head-up display. Instead of the chintzy "brushed aluminum" look on the center-console surround, just paint it the body color, in shiny lacquer. The first-to-fourth-gear skip shift will be an irritation every day of the driver's life. And we don't need no stinkin' doors that open electronically. And really, nothing is more irritating than the three horn beeps triggered by the fob. Does somebody think the owner needs more attention?
CSABA CSERE
The Corvette team was miffed when we dubbed the new model a "C5 and 11/16ths" last February. Now that I've driven the C6, I'm convinced our description was accurate. The C6 feels much like the C5. The character of its powertrain, the feel of its suspension, and the layout of its cockpit and controls will be familiar to C5 owners. That said, the C6 is better in every respect. Straight-line acceleration approaches Z06 territory. Cornering grip is the highest we've ever measured in a Corvette. The interior looks vastly richer. The shifter action is slicker; the exterior shape is more charismatic; the ride is quieter. So why feel bad about retaining an excellent foundation?
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C/D TEST RESULTS
ACCELERATION: Seconds
Zero to 30 mph: 1.8
40 mph: 2.5
50 mph: 3.3
60 mph: 4.3
70 mph: 5.4
80 mph: 6.8
90 mph: 8.2
100 mph: 9.9
110 mph: 12.0
120 mph: 14.0
130 mph: 16.9
140 mph: 20.1
150 mph: 26.3
Street start, 5-60 mph: 5.2
Top-gear acceleration, 30-50 mph: 9.8
50-70 mph: 9.0
Standing 1/4-mile: 12.7 sec @ 113 mph
Top speed (drag limited, mfr's claim): 186 mph
BRAKING
70-0 mph @ impending lockup: 166 ft
HANDLING
Roadholding, 300-ft-dia skidpad: 0.98 g
Understeer: minimal
PROJECTED FUEL ECONOMY (MFR'S EST)
EPA city driving: 19 mpg
EPA highway driving: 28 mpg
C/D-observed: 15 mpg
INTERIOR SOUND LEVEL
Idle: 55 dBA
Full-throttle acceleration: 87 dBA
70-mph cruising: 74 dBA
CHEVROLET CORVETTE Z51
Vehicle type: front-engine, rear-wheel-drive, 2-passenger, 2-door targa
Estimated price as tested: $47,000
Estimated base price: $43,500
Options on test car: Z51 Performance package (includes stiffer suspension, transmission cooler, and larger brakes), head-up display, sport seats, side airbags, heated seats, power passenger seat, power telescoping steering wheel, OnStar
Major standard accessories: power windows, driver seat, and locks; remote locking; A/C; cruise control; tilting steering wheel; rear defroster
Sound system: Delco/Bose AM-FM radio/CD changer, 6 speakers
ENGINE
Type: V-8, aluminum block and heads
Bore x stroke: 4.00 x 3.62 in, 101.6 x 92.0 mm
Displacement: 364 cu in, 5967cc
Compression ratio: 10.9:1
Fuel-delivery system: port injection
Valve gear: pushrods, 2 valves per cylinder, hydraulic lifters
Power (SAE net): 400 bhp @ 6000 rpm
Torque (SAE net): 400 lb-ft @ 4400 rpm
Redline: 6500 rpm
DRIVETRAIN
Transmission: 6-speed manual
Final-drive ratio: 3.42:1, limited slip
Gear, Ratio, Mph/1000 rpm, Max speed in gears
I, 2.97, 7.6, 49 mph (6500 rpm)
II, 2.07, 10.9, 71 mph (6500 rpm)
III, 1.43, 15.8, 102 mph (6500 rpm)
IV, 1.00, 22.5, 147 mph (6500 rpm)
V, 0.71, 31.8, 186 mph (5900 rpm)
VI, 0.57, 39.6, 165 mph (4200 rpm)
DIMENSIONS
Wheelbase: 105.7 in
Track, front/rear: 62.1/60.7 in
Length/width/height: 174.6/72.6/49.1 in
Ground clearance: 3.5 in
Drag area, Cd (0.28) x frontal area (21.9 sq ft, est): 6.1 sq ft
Curb weight: 3224 lb
Weight distribution, F/R: 53.7/46.3%
Curb weight per horsepower: 8.1 lb
Fuel capacity: 18.0 gal
CHASSIS/BODY
Type: full-length frame integral with the body
Body material: fiberglass-reinforced plastic
INTERIOR
SAE volume, front seat: 52 cu ft
luggage: 22 cu ft
Front-seat adjustments: fore-and-aft, seatback angle,
front height, rear height, lumbar support,
lower side bolsters
Restraint systems, front: manual 3-point belts, driver
and passenger front and side airbags
SUSPENSION
Front: ind, unequal-length control arms, transverse
plastic leaf spring, anti-roll bar
Rear: ind, unequal-length control arms with a toe-control
link, transverse plastic leaf spring, anti-roll bar
STEERING
Type: rack-and-pinion with variable power assist
Steering ratio: 16.1:1
Turns lock-to-lock: 2.9
Turning circle curb-to-curb: 39.0 ft
BRAKES
Type: hydraulic with vacuum power assist and
anti-lock control
Front: 13.4 x 1.3-in vented disc
Rear: 13.0 x 1.0-in vented disc
WHEELS AND TIRES
Wheel size: F: 8.5 x 18 in, R: 10.0 x 19 in
Wheel type: cast aluminum
Tires: Goodyear Eagle F1 Supercar run-flat;
F: P245/40ZR-18 88Y, R: P285/35ZR-19 90Y
Test inflation pressures, F/R: 30/30 psi
Spare: none
BY LARRY WEBSTER
September 2004
So, do you still think it's a C5 and 11/16ths?" asked Corvette assistant chief engineer Tadge Juechter in a half-joking, half-serious tone. We had just spent two days driving the newest Corvette the so-called C6 around the hills of southern Virginia and at Virginia International Raceway, and Juechter was repeating, almost verbatim, a headline we'd placed on a preview story of the car. It had probably ticked him off then, but it wasn't showing now.
Although most new-generation Corvettes have been a dramatic departure from the previous version, the C6 Corvette is not a clean-sheet design. And so what? It only proves what we already knew: With the C5, Chevy got most of it right. Even in its last year of production, 2004 after an eight-year run the C5 Corvette was judged a 10 Best Car by us. Corvette chief engineer Dave Hill alluded to that point when he said, "We're not inventing we're perfecting." And perfect they did, making a mix of dramatic and detail changes to the C5 and creating a Corvette that's better in every way.
It's now a tidier package?shrunk by 5.1 inches and riding on a wheelbase 1.2 inches longer. The wide rear flanks have been trimmed an inch. The result is quite dramatic. The Corvette has shed its extravagant proportions for a body that's much leaner and looks more aggressive. The body is still fiberglass, but the design team spent hours in a wind tunnel searching for ways to reduce both drag and wind noise.
Then there's the engine. The basics are quite sweet: A 2.6-millimeter increase of the bore bumped displacement from 5.7 to 6.0 liters. It has 50 more horsepower and 25 more pound-feet of torque (40 more pound-feet in automatics), elevating the output to 400 in both departments, with the redline increasing by 500 clicks to 6500 rpm, the same limit as in the old Z06. The gear linkage of the six-speed manual transmission has been updated for shorter throws and a more precise feel.
The suspension got a thorough redo, too. With new shock absorbers, the length of travel is increased by 0.3 inch in front and 0.8 inch in back. The front caster angle is up one degree for better straight-line stability, the anti-roll-bar mounts are stiffer, the bushings have been revised, and the spring and damping rates have been modified.
The wheels grew an inch in diameter, with 18-inchers up front and 19s in back. The run-flat tires remain, but Juechter says Goodyear softened the sidewalls to improve ride quality.
We had two major complaints about the old car: The drab, monochromatic interior had a cheapness you wouldn't accept in a Cavalier, and the seats felt flat and flimsy. Both are gone. The new seats feature a longer bottom cushion, have supportive bolsters, and hold the driver in place far better than the old ones. The dash was redesigned and uses a combination of textured plastic, vinyl, and aluminum that looks and feels like high-quality stuff. And as before, The Vette is generously roomy inside.
For the first time, the Corvette is available with such luxuries as a navigation system and seat heaters. Keyless entry and start-up with a pushbutton are standard. Electric door latches have been added, so the odd-looking interior door handle is replaced by a simple button. The interior looks and works better, with only one ergonomic mistake: The buttons used to page through the trip computer and a series of various gauges are mounted on the outer rim of the gauge cluster where they are blocked completely from view by the steering wheel.
Nothing in our test car rattled or squeaked?a testament to the C6's rigid frame, changes to which were minimal, other than having its ends clipped. Hill says the frame is only fractionally stiffer and lighter than the old one. More significant, a second transmission mount has been added, and the engine was moved forward a hair (0.07 inch) to make room for a larger clutch that the team thinks will be necessary for the next, higher-powered Z06, due late next year with a rumored 500 horsepower.
Corvette coupes (they all have a removable roof section) and convertibles come in three forms: base, F55 (add about $1700) with adjustable magnetorheological shocks, and Z51. The Z51 package, which will cost about $1500, includes a stiffer suspension, tires that offer better dry-road grip, larger brakes, a six-speed manual with shorter ratios, and a transmission-oil cooler. Expecting a Z51 to be the best performer, that's naturally what we tested.
Before we get to the numbers, a word about ride quality. It's impressively smooth. The suspension communicates the contours of the road and filters out the harshness. Frost heaves cutting across entrance ramps that used to make the hind end jittery are now soaked up nicely. There's a resilience to the suspension that reminds us of BMW's 3-series.
The tires grip fervently, generating 0.98 g on the skidpad. That matches the best of the three Z06s we've tested and vastly surpasses the 0.90 g that our grippiest non-Z06 C5 generated. The C6 has the same balanced feel as the old, with a willingness to slide either end depending on how you play with the pedals. Now, however, it sticks to broken pavement better and is much more accommodating over midcorner bumps. The brakes, too, are wonderful, with good modulation, zero fade, and a stopping distance from 70 mph to a standstill in 166 feet, about the same as the previous car.
The stability-control system has a button that either shuts it off or selects a competition mode that allows more slip before intervening than the fully active mode. It is perhaps the best version of stability control we've ever sampled because it offers an appreciated safety net and yet permits 0.96 g on the skidpad in both fully active and competition modes.
With the system off, the Vette galloped to 60 mph in 4.3 seconds and through the quarter-mile in 12.7 seconds at 113 mph. The C5s we've tested have averaged 4.9 to 60 and 13.4 at 108 in the quarter, and the quickest Z06 [C/D , December 2001] ran 4.0 and 12.4 at 116.
Of course, the C6's more powerful engine is partly why it outruns the C5, but so is its weight. Our test car weighed a minimalist 3224 pounds. That's lighter?by about 60 pounds?than any C5 coupe we've tested. Moreover, the C6 is only 78 pounds heavier than the carbon-fiber $448,400 Porsche Carrera GT. And this mass efficiency was achieved even though the C6 has more features and more sound deadening to quiet the interior. Although our sound-level meter didn't hear a noticeable improvement, back-to-back comparison drives with a 2004 Z06 suggest this new Corvette is much quieter.
One of the goals, Hill says, was to increase performance while improving the Corvette's refinement. This is now a car with an amazingly wide range of capabilities. Around VIR, we drove a Z51 for maybe 20 laps as if it were someone else's, but its performance was so strong that we never tapped the limit of its potential. And it didn't show a single sign that the hot laps were detrimental. It's the perfect everything sports car: fast enough to keep you interested during a day of lapping and refined and comfortable enough to make the slog home, or the daily commute, a relaxing experience.
But even though the C6 is better in every way, Chevy says it will cost roughly $1000 less than the C5. The base car will start at about $43,500 and comes standard with the six-speed manual, which was a $915 option. Our test car had the $1500 Z51 package, a head-up display, heated seats, and OnStar and would probably run about $47,000.
Take any sports car within 20 grand of the Corvette's sticker, and the Vette will flat smoke it. We think the Corvette may also prove a match for the upcoming $70,065 321-hp Porsche 911 and could very possibly outgun the $79,865 350-hp 911S. Oh, and don't bet against the Vette's earning another 10Best spot.
------
The Small-Block Keeps Chugging Along
There was no single trick that produced another 50 horsepower for this pushrod 16-valve aluminum V-8 but rather a series of detail changes.
Dubbed the LS2, the new engine has a larger bore than the LS1 (101.6 millimeters versus 99.0) and a higher compression ratio (10.9:1 versus 10.1:1). Intake airflow was improved by 15 percent, exhaust flow by 20 percent, the valve lift on the cam was raised, and some internal modifications were made to reduce pumping losses. Horsepower is now 400 at 6000 rpm (the C5's was 350 at 5200), and torque is 400 pound-feet at 4400 (the C5's was 375 at 4000 in six-speed manual cars, 360 in automatics).
About 15 pounds were trimmed from the engine's weight by using a thinner-walled exhaust manifold, a smaller water pump, and an aluminum oil pan that requires one quart less of oil. The pan contains a series of compartments and baffles to keep the pickup bathed in oil during high-g maneuvers?even with less total oil capacity.
The engine continues the tradition of alluring low-end thrust and the instant throttle response that we love in a small-block. The Z51's sixth gear is about 14 percent shorter than the C5's, which helps top-gear grunt. The car takes 9.8 seconds to accelerate from 30 to 50 mph in sixth gear and 9.0 seconds to go from 50 to 70. The best C5 needed 11.6 and 11.7 seconds, respectively.
And we're still impressed with how effectively the relatively simple pushrod engine offers power and efficiency, demonstrated by the fact that the C6 makes 400 horsepower and doesn't get stuck with a gas-guzzler tax.
Aero Tricks
To get a sense of just how fanatical the Vette guys are about sweating the details, spend a few minutes with Kirk Bennion, the C6's former lead exterior designer (he's now the design manager). Bennion helped tweak the C6's new shape. It may not look as smooth as the C5, but the C6 actually cuts through the air better and has a Cd of 0.28 versus the old car's 0.29.
Decreasing drag wasn't easy, especially considering that the C6's shorter body and wider rear tires increased drag. With the help of a wind tunnel, Bennion says the team tweaked the airflow in a lot of small areas for an overall improvement.
Take, for example, the area below the front fascia. There's a black air dam that runs across the bottom of the nose. Its job is to reduce the amount of air that flows under the car. It's roughly three-and-a-half inches off the road, and this will sound funny, but designers know it will scrape the surface when, for example, dipping into a parking lot. It's meant to hit the ground, though, and it won't be damaged when it does. (The C5 had a similar piece, but now Hill says the C6's makes less noise when it contacts the road.) The devil's in the details?there are curves at each end of the air dam. The radius of these curves was carefully designed so that air coming off the dam stays close to the body to minimize drag-inducing turbulence.
The engineers also found a high-pressure area just ahead of the air dam that is used to supply air to the front brake ducts. On the C5, the ducts inhaled air from the front of the car.
Chevy claims the C6's top speed is 186 mph. We weren't provided with enough runway to test that claim, but we did see 178, and the car was very stable. Also, the window sealing has been improved, so rather than bow out at 150 and make a deafening roar as the C5's did, the C6's windows stayed put.
As for abandoning a Corvette trademark?pop-up headlights?for fixed units, the team reports that the new lights weigh less, don't take up as much space as the old ones, and don't increase drag when they're turned on. It seems that when it comes to performance, nothing is sacred.
A power-operated softtop makes its debut.
We never had any gripes about the C5's manual softtop. Even though it didn't go down automatically, it was easy to use, and we appreciated the weight saving realized by skipping on the power mechanisms. Now, the convertible has an optional power-operated top, expected to cost about $2000. All the driver has to do is unlock a single header latch and press a button. Automatically, the top folds behind the seats, and a neat, hard boot lowers to conceal it?in about 20 seconds. The power top weighs just 18 pounds and has a soft liner. During our brief drive, it did a reasonable job of keeping out the noise.
All convertibles now have a rear bulkhead that separates the passenger compartment from the roomy trunk, which offers 11 cubic feet of space, or five with the top down. In previous Vettes, the trunk could be accessed from the cabin, at the price of a lot of noise created in that hollow chamber, so it has been sealed up.
With the top down, wind buffeting is fairly well subdued. A wind blocker is in the works. We were surprised to discover just how much we prefer the Corvette convertible to the $76,200 Cadillac XLR. They're built on the same platform, but the Vette is roomier for lanky folks, and its pushrod 400-hp V-8 is 80 up on the Caddy's 320-hp DOHC unit. And, for the first time, the Z51 Performance package is available on the convertible. Who would pass that up for an XLR?
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THE VERDICT
Highs: More powerful engine, attractive interior, comfortable ride, immense grip, fantastic price, supportive seats, balanced handling, short-throw shifter . . . we'll stop there.
Lows: The various electronic features?keyless start, auto door locks, electric door latches?can be more annoying than useful.
The Verdict: Hill and company have given us more of what we liked, fixed what we didn't. A five-star ride.
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COUNTERPOINT
TONY QUIROGA
Nearly everything that bothered me about the last Corvette has been addressed in this incarnation. Where the old car felt like an ill-fitting superhero costume, the new car feels tailored, taut, and less ridiculous. A shorter shifter and lighter clutch-pedal effort make gearchanges a pleasure. The ride is better, too?more compliant and painless. The changes all work in concert to make for a better Vette and a happier driver. But nothing is perfect. The interior is a great improvement over the old in materials and design, but it's a bit uninspired. And there's that lingering odor of resin inside. If that's all I can find to complain about, this Vette is a success.
STEVE SPENCE
Details, details. Good: The shifter throws have been shortened. The tailpipe music is brand-new (like an NSX with attitude). At last, new dash knobs and switches. Not good: Who needs keys that don't work like keys? I would never opt for the head-up display. Instead of the chintzy "brushed aluminum" look on the center-console surround, just paint it the body color, in shiny lacquer. The first-to-fourth-gear skip shift will be an irritation every day of the driver's life. And we don't need no stinkin' doors that open electronically. And really, nothing is more irritating than the three horn beeps triggered by the fob. Does somebody think the owner needs more attention?
CSABA CSERE
The Corvette team was miffed when we dubbed the new model a "C5 and 11/16ths" last February. Now that I've driven the C6, I'm convinced our description was accurate. The C6 feels much like the C5. The character of its powertrain, the feel of its suspension, and the layout of its cockpit and controls will be familiar to C5 owners. That said, the C6 is better in every respect. Straight-line acceleration approaches Z06 territory. Cornering grip is the highest we've ever measured in a Corvette. The interior looks vastly richer. The shifter action is slicker; the exterior shape is more charismatic; the ride is quieter. So why feel bad about retaining an excellent foundation?
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C/D TEST RESULTS
ACCELERATION: Seconds
Zero to 30 mph: 1.8
40 mph: 2.5
50 mph: 3.3
60 mph: 4.3
70 mph: 5.4
80 mph: 6.8
90 mph: 8.2
100 mph: 9.9
110 mph: 12.0
120 mph: 14.0
130 mph: 16.9
140 mph: 20.1
150 mph: 26.3
Street start, 5-60 mph: 5.2
Top-gear acceleration, 30-50 mph: 9.8
50-70 mph: 9.0
Standing 1/4-mile: 12.7 sec @ 113 mph
Top speed (drag limited, mfr's claim): 186 mph
BRAKING
70-0 mph @ impending lockup: 166 ft
HANDLING
Roadholding, 300-ft-dia skidpad: 0.98 g
Understeer: minimal
PROJECTED FUEL ECONOMY (MFR'S EST)
EPA city driving: 19 mpg
EPA highway driving: 28 mpg
C/D-observed: 15 mpg
INTERIOR SOUND LEVEL
Idle: 55 dBA
Full-throttle acceleration: 87 dBA
70-mph cruising: 74 dBA
CHEVROLET CORVETTE Z51
Vehicle type: front-engine, rear-wheel-drive, 2-passenger, 2-door targa
Estimated price as tested: $47,000
Estimated base price: $43,500
Options on test car: Z51 Performance package (includes stiffer suspension, transmission cooler, and larger brakes), head-up display, sport seats, side airbags, heated seats, power passenger seat, power telescoping steering wheel, OnStar
Major standard accessories: power windows, driver seat, and locks; remote locking; A/C; cruise control; tilting steering wheel; rear defroster
Sound system: Delco/Bose AM-FM radio/CD changer, 6 speakers
ENGINE
Type: V-8, aluminum block and heads
Bore x stroke: 4.00 x 3.62 in, 101.6 x 92.0 mm
Displacement: 364 cu in, 5967cc
Compression ratio: 10.9:1
Fuel-delivery system: port injection
Valve gear: pushrods, 2 valves per cylinder, hydraulic lifters
Power (SAE net): 400 bhp @ 6000 rpm
Torque (SAE net): 400 lb-ft @ 4400 rpm
Redline: 6500 rpm
DRIVETRAIN
Transmission: 6-speed manual
Final-drive ratio: 3.42:1, limited slip
Gear, Ratio, Mph/1000 rpm, Max speed in gears
I, 2.97, 7.6, 49 mph (6500 rpm)
II, 2.07, 10.9, 71 mph (6500 rpm)
III, 1.43, 15.8, 102 mph (6500 rpm)
IV, 1.00, 22.5, 147 mph (6500 rpm)
V, 0.71, 31.8, 186 mph (5900 rpm)
VI, 0.57, 39.6, 165 mph (4200 rpm)
DIMENSIONS
Wheelbase: 105.7 in
Track, front/rear: 62.1/60.7 in
Length/width/height: 174.6/72.6/49.1 in
Ground clearance: 3.5 in
Drag area, Cd (0.28) x frontal area (21.9 sq ft, est): 6.1 sq ft
Curb weight: 3224 lb
Weight distribution, F/R: 53.7/46.3%
Curb weight per horsepower: 8.1 lb
Fuel capacity: 18.0 gal
CHASSIS/BODY
Type: full-length frame integral with the body
Body material: fiberglass-reinforced plastic
INTERIOR
SAE volume, front seat: 52 cu ft
luggage: 22 cu ft
Front-seat adjustments: fore-and-aft, seatback angle,
front height, rear height, lumbar support,
lower side bolsters
Restraint systems, front: manual 3-point belts, driver
and passenger front and side airbags
SUSPENSION
Front: ind, unequal-length control arms, transverse
plastic leaf spring, anti-roll bar
Rear: ind, unequal-length control arms with a toe-control
link, transverse plastic leaf spring, anti-roll bar
STEERING
Type: rack-and-pinion with variable power assist
Steering ratio: 16.1:1
Turns lock-to-lock: 2.9
Turning circle curb-to-curb: 39.0 ft
BRAKES
Type: hydraulic with vacuum power assist and
anti-lock control
Front: 13.4 x 1.3-in vented disc
Rear: 13.0 x 1.0-in vented disc
WHEELS AND TIRES
Wheel size: F: 8.5 x 18 in, R: 10.0 x 19 in
Wheel type: cast aluminum
Tires: Goodyear Eagle F1 Supercar run-flat;
F: P245/40ZR-18 88Y, R: P285/35ZR-19 90Y
Test inflation pressures, F/R: 30/30 psi
Spare: none
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