I feel like I've been tipped off the top of the Cresta Run. On rollerblades. And I'm blindfolded. Holy cow, this is scary. To clarify the situation, let's look at the issues.

One: the track I'm on, which is full of closing-radius sphincter-tightening corners, treacherous cambers, conniving double-apex curves and, most of all, blind traps that jump up at you from behind crests.

Issue two, the car. In the Corvette ZR1, we've got 638bhp, in a machine that weighs just 1,518kg fully fuelled and optioned. That's Enzo Ferrari territory.

I don't know the car, and I don't know the track. That combination is so intimidating, I feel like I've about 1,500bhp under my toe.

My first tickle had the rear tyres spinning up in second gear, in a straight line, with the ESP and traction control fully on.

"Oh, it'll do that," chief engineer Tadge Jeuchter told me later, showing only a slightly evil grin. It cuts in only when the car gets properly sideways. And that's in full-nanny mode: after that, there's a 'competitive driving' mode (I'll not deploy that, because I'm not competitive). And then an 'off' mode. If I used that too soon in the learning curve, I would indeed be off.

I'm not saying the ZR1 is dangerous. Far from it. After a few laps, I feel more comfortable. Comfortable? Hmmm, maybe not. Lightning-bolt alert, doing what I can to stay with a car that'll do 0-60 in 3.4 seconds, top out at 205mph and corner at 1g-plus.

More than that, it's gradually apparent that the handling is pretty damned sublime. That, and the brakes, and the grip.

'Right, make no mistake. What we have here is one of the truly great supercars'

Right, make no mistake. What we have here is one of the truly great supercars. Bragging rights ahoy: the ZR1 currently holds the production car record for the Nürburgring.

Although it later becomes apparent on the road that it doesn't feel like one of those brittle, edgy, 'Ring-optimised cars. It's supple and useable.

"Yup," Jeuchter agrees. "Every time we went to the 'Ring and set it up, we'd drive home and find we hated it. So in the end we set it up, then just took it to the 'Ring and tweaked it."

But here's the issue. It's extremely hard to think of this as a hypercar. It's just a Corvette. Never mind the 335-section rear tyres, the blistered wings, the big front splitter, the window in the bonnet bulge, the visible carbon'fibre roof.

To those of us who live in Britain, and who don't see Vettes every day, it's easy to miss those things. So the ZR1 looks like the base Corvette, a car that costs about the same as a Cayman.

Which makes the ZR1's price - £100k, give or take - hard to swallow. It also feels ordinary, but in good ways: easy to drive in town, refined on the motorway, surprisingly supple-riding.

Until you floor it. Then it goes not like a Cayman, but like a Carrera GT. And it's sophisticated. Broadly speaking, a regular Vette consists of a steel frame clothed in fibre glass.

The hotter 7.0-litre Corvette Z06, the one we took to the Isle of Man, has that steel frame replaced by aluminium and magnesium. The ZR1 uses the light frame too, but for the skin the glass fibre is replaced by carbon fibre.

Most of it painted, but some of it lacquered for show, glinting thousands of tiny diffraction-rainbows in the summer sun.



The ZR1 has a 6.2-litre V8 with a supercharger on top, and on top of that an intercooler, the bit you see through the bonnet peep-hole.

Pur-leeze don't go on about pushrods: the fact that it's a pushrod engine rather than a four-cam makes it far more compact, which is the only way they could fit a blown engine into the Vette's bay, because, again against the prejudicial view of American cars, a Corvette is roughly the same size as a 911.

And it's an engine of awesome, shattering authority. It's not just the 638 horses, it's the torque that makes the earth move. The peak is 603lb ft, and there's upwards of 540lb ft from 2,000rpm to 6,000.

You've got a big head-up display to help you time your gearshifts, but, honestly, you can change up early if it's convenient. The torque'll always dig you out. It also makes the 7.0-litre (but unblown) Z06 feel decidedly peaky.

The ZR1 gets carbon ceramic Brembos as standard. I never got used to their power. But they're quiet and progressive too, even when they're cold.

By the way, the rear discs in the ZR1 are the same size as the front ones in the Enzo. The ZR1's fronts are, of course, a size or two larger again.

There's fancy electronics in the ZR1's chassis. The stability controls do a silky smooth job of containing your goof-ups, and if you drive properly they'll let you use pretty much the car's full scope. In fact, in competitive mode, it's on for fairly wide-angle second-gear drifts.

There's also a brilliant adaptive damping set-up, by the offices of our new best friend, the magnetorheological method.

OK, back to that tricky track - it's GM's own development circuit near Detroit. What makes the ZR1's handing so great? The turn-in is accurate and measured, the roll well-contained, the mid-corner balance as deft as a plate-spinner.

The traction out of the bends is remarkable too, though if you start taking liberties with all that power, the tail end will graciously, but firmly, point it out.

'It'll do supercar too: thrill you, challenge you, launch you into multidirectional G-loadings'

On the road, the bag is a little more mixed. Those adaptive dampers allow softer springs than the Z06 (I drove them back-to-back to calibrate myself against the Isle of Man experience), which means fewer shocks going through the car and through you, and a better sense of precision over the kind of lumpy roads we get in Britain.

But some intrinsic Corvette debits remain: the steering doesn't really have much feel, and there's a slight sense that different parts of the car are jiggling away in different directions.

I'm thinking the dynamics are better than an Aston DBS, but you don't get the delicious precision of a 599.

Still, the Vette is a wonderful car. No one can object to it on grounds of ability. But on other grounds, object to it they will. For a start, poor GM will get slagged off as flat-footedly insensitive for launching this car at the very moment the gunwales of the Good Ship Detroit were being engulfed by the chill waters of recession.

But let's knock that into the long grass: they'd been developing it for years, and it was too late to stop. And hey, no one has a pop at Ferrari for making extravagant cars in thin times.

More seriously, people will object that the ZR1 looks like, and has a cabin like, a car of half the price.

But it has the performance and the chassis to match an SLR 722 and other tackle three times its price. So you have to decide what you call value.

Generally speaking, the faster supercars get, the harsher and more tiring they are. The ZR1 isn't like that. It's a comfy, refined GT. But it'll do the supercar bit too: thrill you, challenge you, launch you into multidirectional G-loadings.

That sounds like a reasonable definition of value to me.

By the way, the rear discs in the ZR1 are the same size as the front ones in the Enzo. The ZR1's fronts are, of course, a size or two larger again.