Road Test: Audi A8 3.0 TDI Quattro 4dr Tip Auto

Everything about the new Audi A8 is softly spoken. It doesn't so much drive down a motorway as ooze over it. The engine is muted hypnotic thrum, the new eight-speed gearbox flirting through the ratios like it's playing a musical scale. Wind noise is non-existent; road noise dropped to a barely-there hiss. Even the suspension is quiet - you feel bumps if you hit them hard enough, but you don't hear them. Effortless coccoonery, deft and premium-feeling isolation.

The cabin is a grand sweep of tailored perfection, with innumerable threads of super-gadget woven into an architecture that doesn't threaten with button frenzy, or get all impenetrable by congealing functions into a set of submenus accessed by a computer mouse with pretentions. There's a Multi Media Interface screen that pops up out of the dash, controlled by a simple scroll-and-click wheel. Gears are accessed via a lovely gear selector that looks a bit like the throttle control from an aeroplane, which then acts as a kind of lazy wrist-rest when you're playing with functions on the move. The seats adapt and move in ways your body may not even accommodate. For the first few tens of minutes, all you do is sit in the thing, pushing and prodding switches.

Drive it, and the impression is that Audi is taking its flagship model very seriously. The air suspension is a serious filter: even when you play with the Audi ‘drive select' system, which alters damping rates, throttle response and gearbox strategy and go faster, it remains supple and absorbent. All the models we drove featured quattro four-wheel drive, and even though the general feature is one of gentle understeer, if you option the sports differential, you can even provoke a whiff of oversteer as torque is shuttled to the outside wheel. 

We'll be offered three engines at launch in the UK: a pair of 4.2-litre V8s - a 370bhp petrol and a 350bhp, 590lb ft diesel - and a more practical 250bhp 3.0 V6 diesel that should see 70 to 80 per cent of the business in the UK, thanks to a very impressive 42.8mpg. Later this year, we'll see another version of the V6, with a more parsimonious bent and front-drive only, chucking out a scarcely credible 159g/km of CO2 and returning an attractive 47.1mpg on the combined cycle, while still pumping out just over 200bhp. Which is pretty impressive when you consider this is still a large luxury car that can put the green-eyed smackdown on the neighbours.

Funnily enough, the pick of the bunch is the stock V6, a new engine that features a revised injection system. But that's not to say that it isn't impressive as hell. The figures speak for themselves, but 250bhp, 405lb ft, 0-62mph in 6.6 seconds, 155mph and 42mpg are worth repeating. It's a more intuitive car to drive down a twisty road than either of the slightly heavier-feeling V8s too - it feels lighter, more wieldy, slightly more connected. Both V8s are wonderful, but they seem denser, and more suited to monstering larger, Germanic roads. Saying that, if you want to cruise through Germany at 130mph, the hugely torquey 4.2-litre V8 is a proper autobahn-stormer.

And the tech will give the Mercedes S-Class a decidedly close run for its money. You can option the usual high-end luxo-glitter like nightvision cameras, a 1,460-watt Bang & Olufsen stereo, massage chairs and the like, but the A8 brings a few new options to the table that'll have geeks blushing. There's now a touchpad with handwriting recognition for programming functions like satnav, there's Google news and weather streamed direct to the car and there's the ability to make the car into a mobile WLAN hotspot. It's also got an advanced Audi ‘pre-sense' anti-crash system that can check whether a car is indicating to pull out, and modulate the adaptive cruise to suit. Better than that, laterin the year a module will allow the satnav to talk to the gearbox, adaptive cruise control and swivelling, all-LED lights, allowing the A8 to make decisions about how it might react to oncoming hazards. Hello HAL.

The issues are few and far between. Perhaps the most obvious one is that the new A8 doesn't have the instant  visual impact of the cars that went before it. It looks better in real life, but there's a wealth of detail that isn't quite right. Take the headlights. Now, I'm a fan of making lights interesting, but the lightbar that nestles inside the headlamp on the A8 doesn't suit it. Switch the lights off, and the A8 hasa slightly frowning but pleasant physog. Switch the lightbar on, and the car looks pinched and grumpy. And although there's a lot more texture in the surfacing when yousee it in the metal, there's too much generic Audi DNA in the flow. From the back, at a distance, this really does look like an A4. Not ideal.

Also, the dynamic steering weights up strangely around corners, changing the ratio of the rack and generally feeling about as honest as a market-stall Rolex. It might suck out kickback and give reliably damped steering, but given that you can chuck the new A8 around pretty effectively, it holds the car back a bit.

Overall, then: not an instant hit with the styling, but enough polish on the rest of the car to warrant consideration - or at least a reprieve until we figure out whether we'll  grow to like the funny face.