America muscles in...

While Australia prides itself on locally built V8s - the quality and performance of which are reaching giddy heights these days - the American invasion is quietly starting to take effect.

While the likes of Ford and General Motors prefer their local representatives to take centre stage on the showroom floor, we are slowly but surely seeing a move towards colossal vehicles of incredible straight line speed.

This wouldn't have happened if there was no demand; so why are we so obsessed with more horsepower and larger displacement?

Perhaps it differs from person to person? Some may prefer tyre melting horsepower and the kind of torque that literally pins you into the seat cushions, while others get their thrills from the left-rights and g-forces of a twisty mountain pass.

Whatever gets your adrenaline flowing on the black-top, there's likely to be something that piques your interest in the now growing line-up of American models, and with more Australian models now heading across the pond, expect the Yank-tanks to arrive more frequently on local soil.

Ford now sells the Mustang Cobra as part of its range, a rather lethal 260kW coupe, and Chrysler has just recently started importing its 'retrogressively' styled Viper.

So what about the General - arguably the world's biggest automaker? Are his troops going to invade and, if so, what would be the main artillery?

The revamped 2003 Chevrolet Corvette Z06, without a doubt.

The Z06 is GM's hero car in the States and, while the specifications speak volumes for its performance, there's a lot more to the thundering 'Vette than just its famous small-block 350 cubic inch V8.

The new Z06 model, released in the States at the end of 2002, gets a bump up in power among other things.

Using a variant of the 16-valve 5.7-litre Gen III eight cylinder that gives the VY Commodore SS life, the Chevy engineers seem to be a little more aware of how to best tune the engine - not surprising really, because they designed it!

The LS6 is slightly more powerful than our home-grown 300kW HSV-Y GTS, with 302kW, or 405bhp for the imperialists.

More telling of the 'Vette's spirit, however, is its 0-100km/h sprint time of 4.1 seconds - not bad for a car that weighs in at roughly 1400kg.

And how's this for fast: it does the quarter mile in 12.4 seconds at 185km/h. In layman's terms, it means you'll be down to the milkbar and back before the ad break has finished.

But how is it that the Z06 is so much faster than the HSV GTS, with only a 2kW advantage? Simple - torque.

While the 2003 HSV-Y GTS derives 510Nm @ 4800rpm from its GM-built engine, the Chevrolet makes 542Nm at the same engine revs. The easiest way to explain this disparity would be cash-flow, and essentially the Americans have a lot more of it.

The LS6 'breathes' much better at higher revs, where all that power hits, and this is because induction systems, camshaft and cylinder heads have been tweaked for better peak performance.

As the Chevy press release explains: "A positive crankcase ventilation system improves oil control during racetrack and high-lateral-acceleration maneuvers.

"Plus, a unique-to-Z06 titanium exhaust system (mufflers and tailpipes) has less mass and more strength than aluminum or magnesium." Where do we sign?

While the power and torque stats are impressive, just as important is the transmission and suspension, as getting the power from the engine to the rear wheels efficiently is easier said than done.

Making use of a customised T56 six-speed manual transmission built by Tremec (the same one used in the new 8.3-litre Viper) and rear limited slip differential, the new model puts its power down with aplomb, and to keep fuel consumption down, there's a special 1st-to-4th gear mechanism that kicks in when engine revs are low, such as city driving.

The sort of power that the Z06 offers, and more importantly the way in which it is delivered, dictated that Chevrolet had to include a number of safety features, the most obvious of which include four-wheel ABS, traction controls and stability control.

But the Z06 also ships with a system called Active Handling, which, in simple terms, combines individual wheel braking and traction control to ensure things don't get too out of hand...

New to the 2003 'Vette are cast spun wheels, which reduce wieght by couple of kilos over the outgoing model. Up front, the Z06 gets 17-inch wheels, shod with 265/40ZR tyres, while at the rear barrel-like 295/35ZR cover larger 18-inch rims.

Inside, the Z06 offers the usuals, such as cruise control - which is a bit of an oxymoron really. One rather cool techno gadget included is the HUD, which has been used on a few models in the past. It basically projects engine revs, speed and an number of selectable options (fuel, oil, engine telemetry etc) onto the inside of the windscreen at an angle that allows drivers to barely take their gaze off the road ahead.

And what about styling? Depending who you ask, it's a thing of beauty or an ugly, fat-arsed wedge. Designed in the wind tunnel, the first C5 Covette (which the Z06 is based on) arrived in the States during 1996 and everyone panned it. Today, however, people are more welcoming - perhaps time really does make the heart grow fonder?

The roofline is similar to the superceded Viper, with its 'double bubble' styling cues and while the rear end is a bit frumpy, those tail-light and closely spaced quad trumpets are unmistakable.

At the end of the day, the chances of the Z06, or any 'Vette for that matter, coming to Australia through official channels are slim.

The GM high-ups in the States are very pleased with Holden's performance in Australia and in export markets, such as the Middle East, and converting the Corvette to a RHD is probably not at the top of their "to-do" list. Still, three years ago the same could have been said about the Ford Mustang and Dodge/Chrysler Viper, so it's not a foregone conclusion by any means.

You will see the odd 'Vette cruising around town, as there have been quite a few imported over the last three decades, but as it stands the new Z06 is one helluva car that can compete against the best the world has to offer. The American invasion, though, has only just begun...