Audi S8

The new Audi S8 can be specified with 385mm ceramic brake discs. Funny, I was more excited about that than the Lamborghini-sourced V10 engine in residence under its bonnet. I suppose the shock of a 5.2-litre V10 engine (up from 5 litres in the Gallardo) powering a big, refined saloon had worn off since I'd seen the headline-grabbing tech spec for the new S8 at the Tokyo motor show in November. But I hadn't clocked the brakes, and, although it's a bit geeky, I can't help associating ceramic brakes with the likes of the GT3 RS, 360 Stradale and Zonda F - my sort of cars (ignoring the small matter of the price, of course).

Okay, so you might not share my excitement over the brakes, but you've got to love the concept of the S8. The Gallardo's engine has been bored out to 5204cc, equipped with Audi's FSI direct petrol injection technology, and massaged for torque rather than pure horsepower. It doesn't rev to the Gallardo's screaming peak of 8000rpm, but even so, the Audi-fied V10 still produces 444bhp at 7000rpm and a strong 398lb ft at 3500rpm.

With the enormous traction afforded by the quattro four-wheel-drive system, that's enough to launch the 1940kg S8 to 62mph in 5.1sec and thump it well into three figures before the acceleration starts to fade. Our car had a 'press-launch speed- limiter' which saw it sail past 155mph and on to around 170mph - with plenty more to come.
So, it's comfortable, practical, beautifully-constructed and has the heart of a £130,000 Lamborghini - all for £70,000. It sounds almost like a bargain...

Until, that is, you remember the 501bhp, V10-engined, £61,775 BMW M5. But this is a very different animal to the M5 or even the deftly balanced and similarly priced Maserati Quattroporte. It's more appropriate to look at the S8 as a cut-price Mercedes S55 AMG: a smooth, sophisticated and relaxing luxury saloon that just happens to have some serious firepower at its disposal should you require it.

Perhaps that sells it short. If the S8's ceramic brakes hint at its performance potential, then the adoption of the new RS4's 40:60 front:rear torque split sends a clear signal that this car is intended to attack corners with as much enthusiasm as it devours motorways. If you just want waftability then the £73,580 6.0 W12 is the big Audi for you.

Twist the key, or depress the starter button, and the V10 flicks into life instantly, idling loudly enough to let you know that you're in something special. Slide the 'box into D and tickle the throttle. As the speed picks up, the exhaust note almost disappears. It's as quiet as any other A8. The ride is exceptionally good, too. You'd never guess the S8 is running on 20-inch wheels with aggressive rubber and a more sports-orientated version of the A8's adaptive air suspension that lowers the ride height by 20mm.

Nudge the gearlever across to activate the paddles mounted on the back of the steering wheel (they're always active, but if you don't engage the true manual override the electronics will soon reassert themselves), start to exercise the engine and the S8 really delivers. It's not S55 AMG-fast, in fact initially it doesn't feel as accelerative as you might hope, but the delivery is beautifully judged. There's plenty of creamy torque and as the revs rise and the exhausts start to deliver their tuneful offbeat howl, the S8 gathers momentum with an easy, magical stride.

Nestling beneath this deep lustre of effortlessness there's taut control. The body feels extremely well tied down and when you start to test the grip and composure of the S8 it simply shrugs its shoulders and gets stuck in. For such a heavy car its resistance to roll is superb. Grip is very strong and the S8 manages to feel both utterly secure and yet nicely malleable.

The steering, despite being 10 per cent quicker than that of other A8s, would benefit from a shade more weight, but the six-speed ZF automatic gearbox is superb. It hits up-changes home with such speed and precision that you'd swear it was equipped with the VW Group's DSG system. Even better, the clever 'box delivers a rev-perfect blip between downshifts every time. It's these little things that help give the S8 such a compelling split personality. It plays the cruiser role perfectly, but it's surprisingly good fun when you're in the mood for something a little more taxing.

You won't be surprised to learn that ultimately the S8 will understeer gently rather than spit you sideways, but in a two-ton car of such generous proportions it'd be churlish to complain about that. Instead, just revel in the security, the glorious noise and the sense of occasion.

Oh yes, I nearly forgot... The ceramic brakes work brilliantly.

Specifications