The A8 was where it all started for Audi, a landmark luxury saloon launched back in 1994 that proved at last that this German marque really could match - and in some areas beat - its better-established rivals.

It was then (and still is) the only car of its kind to be constructed around an aluminium spaceframe, lighter and stronger than its rivals for what the Ingolstadt brand calls 'a responsible approach to luxury'.

The second generation version, launched in 2003, gave us a better idea of what that meant, with a slightly softer and more user-friendly approach to hi-tech efficiency.

But it wasn't quite enough.

Rivals - Mercedes' S-Class, Jaguar's XJ, even BMW's 7 Series - well, they may not always have been able to match the A8 on paper but for many buyers, they were that bit more appealing in the driveway.

A further evolution was needed - this Mk3 model, which arrived in 2010. This is still Audi's flagship, even if it's no longer the most expensive car the company makes, and as such, it must showcase the technology that the brand hopes will lift it clear of its two closest German competitors.

So its structure is lighter yet more rigid and it's faster yet more fuel efficient.

Top executives, Audi promises, will also find it has a wider breath of abilities than its rivals: where a Mercedes S-Class is all about luxury and a Jaguar XJ about driving dynamics, this A8, we're told, has a multi-faceted personality that can be all things to all boardrooms.

And it'll reward you in the driveway as much as it will in the drive home.

Most of all, they say, it'll be a car that you're not only impressed by but one that you can also fall in love with.

At the wheel of the most popular 3.0-litre TDI quattro diesel model, let's find out if they're right.

If somebody had told us ten years ago that we'd be driving a two-tonne diesel-powered limo capable of accelerating from rest to sixty two mph supercar-style in just over 6s, we wouldn't have believed it.

Yet that's exactly what this 262PS 3.0TDI quattro A8 can deliver - thanks to a prodigious 550Nm of torque.

A glance at the spec sheet might suggest the A8 to have lost the significant weight advantage the MK2 model used to have over its rivals, courtesy of its aluminium spaceframe underpinnings.

But that's to ignore the way that this Audi is almost unique in this class with its standard fitment of quattro four-wheel drive.

On any road, in almost any conditions at almost any speed, this A8 feels better the harder you drive it, solidly planted and reassuring in a way that no rival can better and few can match.

Whether you'll feel the same about the standard and very undoubtedly clever 'Drive Select' electronic chassis tuning package is another question.

It's this, Audi claims, that gives the car it's multi-faceted personality as the driver chooses between 'comfort', 'auto' and 'dynamic' modes, each of which alters the suspension settings and the transmission shift points. The rest of the A8 experience is luxury personified, with everything from the headlights to the seatbelts programmable to your mood.

Highlights? It's hard to pick one.

Maybe the effortless ease of the silky-smooth 8-speed tiptronic automatic gearbox with its steering wheel paddles and 'Drive' or 'Sport' shift programmes.

Or perhaps the supple ride delivered by the multi-link air suspension.

Then there's the awesome refinement delivered by the whisper-quiet TDI engine (a slight rumble on start-up is the only diesel give-away) and the double-glazed glass.

Though this isn't quite the most rewarding driver's car in its sector, all these things are factors in its status as arguably the most complete one.

This A8 is an impressive achievement, with this 3.0 TDI quattro model the best all-round choice in the line-up.

As it should be, this is a showcase for the Audi's best and most advanced technologies.

Aluminium construction, quattro all-wheel-drive, advanced petrol and diesel engines and mind-boggling hi-tech features - they're all there and they come together with classy design and robust build quality to create a formidable motorcar. But is it one that you can bond with, a luxury saloon you'll love as well as admire? The answer depends upon the owner of course: some may still find the A8 a little remote compared to a wood-panelled Jaguar, a status-conscious Mercedes or a proudly opulent BMW.

I'm guessing though, that a significant number would find this Audi a better all-round choice.

Hugely capable, innovative, beautifully built and able better than any rival to alter its dynamic character to your driving mood, this is the car that rivals always feared Audi would build.

And if you're in this market, it's one you need to try.

Pricing for the 3.0 TDI quattro is between £55,000 and £58,000, depending upon the spec that you choose, with a £4,000 premium if you want the long wheelbase bodystyle.

When comparing with rivals, make sure you compare like-for-like - ie.

against a Mercedes S-Class rather than an E-Class.

Let's do a bit of that.

The 3.0 TDI quattro A8 that most will want will cost you around the same as a comparable BMW 730d or Jaguar XJ 3.0 V6 Diesel, but save you around £3,000 on a Mercedes S350 BlueTEC. Whichever spec you decide upon, equipment levels shouldn't disappoint.

Safety-wise, there are eight airbags, stability control of course and Audi's clever pre-sense system, which automatically activates the hazard warning lights, closes the windows and tightens the seatbelts if it thinks an accident is unavoidable.

Pay more and in such a situation, it'll automatically brake the car for you if it thinks you haven't done so sufficiently, with cruise control that notices other cars indicating in other lanes and adjusts itself to suit.

There aren't many aspects of this car I can cover without talking about aluminium.

Here's another.

Thanks to its increased use, this A8 is as much as 200kg lighter model for model than the previous generation car.

As I've said earlier on, much of that advantage is negated by the addition on most models of the heavy quattro 4WD system but even allowing for that, this car's fuel returns are still impressive, aided further by a stop-start system to save fuel in urban traffic and Audi's Recuperation system which recaptures kinetic energy to charge the battery when the car is coasting or braking.

The result is 49.6mpg on the combined cycle for this 3.0 TDI quattro model and 149g/km of CO2.