Road Test of the C6 Z51 Vette

[Gripenfelter]

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.



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 (see sidebar "C6 Convertible") 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.



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.



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.



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 moderate excessive

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

[iceburns288]

That was a good issue of Motor Trend... good article too. The cutaways were really neat, it's cool to see something like that.

[C4S]

I saw that too .. but ... again, like the last Corvette ..
got quite different performance gap between different road test ... I think road and track ( ? ) or other magazine got 4.8 second or 4.9 second for 0-60mph .. still even take the average, is about 4.6 second ... when the C5 came out ... I saw from 4.6 second to 5.2 second .. I can understand 0.1 or 0.2 second different between magazines . .. or may be just between magazines ?? Motor Trend always got the "quickest" time, and Road and Track always got the "slowest" time .. Car and Driver always has quicker time then R&T or other magazines too ...

Does it mean Motor Tread has better drivers then other magazines ?

[Gripenfelter]

This was taken from Car And Driver.