Australia's Four-Door Corvette Z06 It all starts with the Holden GTS, a short-wheelbase version of the Holden Commodore SS that we know as the Pontiac G8. Although there's a bigger 427-cid engine under the hood, there are only a minimal 20 pounds extra over the front tires. By Michael Stahl, Contributor Date posted: 08-18-2008 503-hp 427-cid LS7 V8 - Six-speed manual transmission - Six-piston brake calipers - 427 cars to be built If you ever wanted a four-door Corvette Z06, it figures that Australia is the best place to look. The 2008 Holden HSV GTS W427 mates the Z06's hand-built, 7.0-liter LS7 V8 with the short-wheelbase GTS version of the Holden Commodore. It's not only Australia's most powerful car ever but also the most expensive car ever to be built Down Under. Given the Aussie-developed sedan's current 361-horsepower 6.0-liter LS3 V8 and the impending use of the Tremec TR6060 six-speed manual transmission (a combination we should see soon in the 2009 Pontiac G8 GXP), it's perhaps not surprising that Holden Special Vehicles (HSV) would crank up the whole idea another notch. What may surprise you, however, is that the HSV W427 — of which HSV plans to build up to 427 examples — costs almost twice as much as a Corvette Z06 — US$142,550. Heck, it's almost US$20K more than the 2009 Chevrolet Corvette ZR1, GM's most expensive model. In Australia, where we don't have Corvettes, the W427's AU$155,500 price tag puts it into the mix with the BMW M3 and the Mercedes-Benz C63 AMG. It's a big step. In the Spirit The dry-sump 7.0-liter V8 fits right in, although a Hoover-style air intake has to be added. All the interior architecture is familiar, although HSV adds dramatic upholstery and Recaro-esque seats. It's said that the plan for the 2008 Holden HSV GTS W427 was hatched two years ago when auto industry tycoon and HSV owner Tom Walkinshaw (an ex-racer) was sharing a bottle of fine scotch with Denny Mooney, then chairman of Holden. (We're guessing that Walkinshaw, born and bred in Scotland, chose the scotch.) Mooney had been the vehicle performance padre at GM Engineering in Australia and was looking toward Holden's 60th anniversary in 2008, so he asked Walkinshaw what he intended to do to mark HSV's 20th anniversary the same year. Seems to us that another quiet night in Tom's scotch cellar would be as good a way as any. But that would be to deny several hundred HSV fans the opportunity to contribute AU$155,500 to the drinks kitty. Ninety deposits have already been taken for the W427, making HSV's production goal of 427 examples look attainable. Several are doubtlessly destined to share dehumidified garage space with their 1970s Aussie muscle-car forebears, examples of which have lately been nibbling at prices of a half-million dollars at auction. Rising From Defeat HSV's instrumentation looks snappy but proves illegible in real life Walkinshaw still feels the sting from the failure of another project with the 427-cubic-inch GM V8, the 2002 HRT 427, a big-motor version of the Monaro that we knew as the last Pontiac GTO. The stripped-down, 7.0-liter Corvette C5R-powered prototype attracted 50 firm deposits, which had to be refunded when HSV realized the proposed $150K price tag just wasn't going to add up to any profit. Funny, because in April this year, one of the two HRT 427 prototypes built was sold for an Australian record AU$920,000. The buyer, a rural home builder known only as "Chooka," has a stash of some 20 classic Holden Monaros, not to mention a private racetrack on his property. The pitfalls in Walkinshaw's experience with the hand-built HRT 427 shaped the HSV W427, which features a stock Corvette Z06 drivetrain that has been inserted into what's essentially an HSV GTS — a far more affordable proposition. Unlike the HSV's LS3-powered models, which are built on the Holden production line in Elizabeth, near Adelaide, the W427 has to be de-LS3-ed and rebuilt at HSV's headquarters in Melbourne. The 427-cubic-inch engine is almost identical in length and width to the LS3, although it can be mounted slightly lower because of its dry sump. This occasioned some redecorating of the engine bay, with a fabricated alloy oil tank displacing the original air box. An oversized Hoover-style snout takes over the air box's function and sits directly ahead of the engine, sucking cold air. At 4,122 pounds, the W427 is almost 1,000 pounds heavier than a Corvette Z06. Appropriate ECU recalibration and custom four-into-one exhaust headers explain a small difference in power output, as the W427's V8 delivers 503 hp at 6,500 rpm and 472 pound-feet of torque at 5,000 rpm. End result: the W427 is easily HSV's — and Australia's — fastest four-door ever, with 0-100 km/h (62 mph) acceleration in 4.7 seconds (a second slower than a Z06) and a standing quarter-mile in the high 12s. Right on the Nose Two-position MRC dampers provide a choice of ride quality for both passive and aggressive personalities. The 503-hp LS7 V8 makes this a quartet worth listening to. If littlies like the BMW M3 and Merc C63 AMG can get away with V8s, it figures that a great big GTS should be able to cop a big-block. The LS7 adds just 20 pounds over the GTS's front end, and overall the HSV car weighs just 60 pounds more than an LS3-engined GTS. The W427's suspension has been addressed with 30 percent stiffer spring rates all around and the Magnetic Ride Control (MRC) dampers recalibrated accordingly, while the ride height is lower by 0.8 inch (which will keep you alert on Australia's rugged rural roads). Like the bolt-on bodywork, the 20-inch wheels have been styled by HSV designer Julian Quincey and they're a standout — literally. The curb-crunching spokes are scalloped to accommodate six-piston brake calipers gripping 15-inch floating rotors. These unique new calipers boast a 50 percent increase in brake-pad contact area than HSV's previous premium braking system. The best brake pedal feel this side of Zuffenhausen and equally masterful ABS calibration allow aggressive exploitation of the grip provided by the W427's Bridgestone Potenza RE050A tires (245/35R20s in front, and 275/30R20s in the rear). Working-Class Hero HSV-designed wheels conceal six-piston calipers with extra-large brake pads. Pay your AU$155,500 and you get one of these. This big-block, big-buck bruiser does aggression very well. The rumbling grunt of the LS7 might lull one into believing it's all about the bottom-end power. But that torque peak at 5,000 rpm tells the other side of the story. The bottomless well of effortless grunt and the softer of the two MRC suspension settings make the W427 perfect for the ham-handed, blue-collar millionaire to sloth around. The clutch action is pleasantly light and progressive, although the TR6060 gearbox is a little less so, being knuckly in its action and prone to balk in its narrow gate if hurried. At 62 mph, the overall gearing has the engine rolling over at 1,100 rpm in 6th (the instant fuel readout indicating 25 mpg), 2,300 rpm in 5th and 2,800 rpm in 4th. And if you drop to 3rd, you get to meet the other engine.... Lucky Sevens: 7,000cc at 7,000 rpm When you're Australian, driving this way comes naturally. Anywhere above 3,500 rpm, the LS7 mill is making more torque than an LS3's peak torque output of 400 lb-ft. By 4,500 rpm it's a rev-hungry, race-ready monster, pulling absolutely all the way to the cutout at 7,000 rpm. The car hunkers down on its haunches, squirming gently as it truffles the road surface for traction. The vacuum-operated valves of the mufflers open wide to decrease backpressure and unleash a gravelly, big-hearted howl. And the fun doesn't end at the first bend. The steering effort is a tad lighter than one expects, but its feel off-center and under load is excellent. Here ends any fear of nose-heavy handling, as the confident, responsive turn-in is true to the Holden GTS, while the rear suspension telegraphs its intentions. The W427 is simply operating a rung higher than the LS3-powered GTS in every way — braking capability and feel, turn-in grip and the power to smear the rear tires against the road surface as you fine-tune the car's attitude on exit. With the suspension damping at its softest setting, there's perceptibly slower rebound response and the occasional, small stumble over bumps in the corners. On the flip side, this setting helps one better feel the rear end responding to throttle inputs. In the firmer setting, the W427's ride quality is a remarkable achievement. We'd reckon that this 1.8-ton sedan's point-and squirt prowess would keep it in touch with smaller European rivals like the M3 and C63 AMG, even on tighter roads. Now, About That Stiff Scotch Big six-piston calipers deliver enough braking power to control the W427's speed. The GTS is a short-wheelbase version of the Holden Commodore sedan, so it doesn't have lots of rear-seat legroom. Of course, the 2008 HSV Holden GTS W427 isn't an AU$150,000 Mercedes or BMW; it's an AU$150,000 Holden. Despite the car's amazing dynamic ability, there are subtle signals of its working-class origins in body-drumming, low-speed drivetrain lash, stamped door hinges and hard interior plastics. And aside from specially trimmed Recaro-esque seats, plus instrumentation that's more fussy and illegible than the standard Holden stuff, there's very, very little aside from the engine to differentiate the W427 from the GTS model that costs less than half as much. For this money, you ought to get either loads of luxury or loads of lightness. But there's no tailored sound system, no seat massage or air-bladder lumbar trickery, no sat-nav or television. And the rear wing is the only carbon fiber we saw. The 2008 HSV W427's LS7 drivetrain is phenomenally powerful, the well-sorted chassis gives great grip and feel, the two-stage MRC dampers deliver impressive ride quality and the brakes are up to the task. But collectibility aside, the W427's price is either cynical or hysterical, as too much of the car betrays its humble Holden roots. This is the fastest and most capable Aussie four-door yet; but pricing must be about heart, 'cuz it ain't all in the hardware.