Audi has created a bit of a conundrum for itself. Its range of cars all sit firmly at the pinnacle of automotive engineering. They are all beautifully built with obsessive attention to detail and that means for those of on more limited budgets we can buy an A1 and enjoy the same luxuries as we would in an A3, or an A3 instead of an A4 and so on.

Spare a thought then for the poor old A8 which sits atop the range. Not only does it face some serious competition from the Mercedes S-Class, 7-Series BMW and Range Rover, but also from within its own camp.

The A8, doesn’t just have to be very good. It has to be exceptional and, spoiler alert, for the most part it is just that.

It’s surprising, then, that the styling is on the conservative side. Not that it isn’t handsome, and it’s sheer size affords it a presence that it’s familiar face might not otherwise, but from a distance it doesn’t look that different from is less salubrious siblings.

It’s likely, however, that potential buyers may be drawn to the big Audi’s less ostentatious exterior and, should they be tempted beyond just browsing, they’ll find themselves behind the wheel – or in the back of – a well-built and well-equipped executive salon with the credentials to compete with the best in class.

The cabin is just as well put together, just as aesthetically and ergonomically pleasing, as anything else in the Audi range – which is to say that the standards are very high indeed – but with a few extra bells, whistles and more than a sprinkling of cutting edge technology thrown in.

The materials are all high grade with plenty of leather, veneers and inlays to lend the passenger space the required level of comfort and luxury.

The SE model provides the solid foundations upon which the enviable range is built and comes replete with 18in alloy wheels, adaptive air suspension and LED headlights and electrically adjustable heated seats that, if they had sleeves, would have a little party trick hidden up them that I’ll come to later.

The 3.0-litre TDI Sport spec that I tested swaps out the standard seats with, er, sports ones, adds an inch to the diameter of the alloy wheels and replaces the stereo with a Bose surround-sound system.

One option fitted to my test car that is particularly worthy of mention is Audi’s night vision assistant which uses a thermal imaging camera – mounted behind the left-most ring of the Audi badge – that reacts to the heat radiated by objects – such as wild animals and stray people – ahead of the vehicle.

The black and white image is displayed on a screen between the instruments and, although the camera has a fairly narrow field of view – just 24 degrees – it can, and does, detect warm-blooded wildlife much further in front of the car than anyone who doesn’t have supersonic sonar radar to guide them and go by the name of Batfink.

It would, however, be much more exciting if the images could be projected onto the windscreen for a true head-up display overlaid on the view out the front. Next year perhaps?

The seven-inch multimedia display rises out of the dashboard ceremoniously when you start the engine and is controlled via a touchpad next to the gear selector. You can connect your music player using the Audi Music Interface that gives you control of your device using the car’s MMI (Multiimedia Interface) and multifunction steering wheel.

Now, back to the seat’s little secret. If you enjoy a massage and, let’s be honest, who doesn’t then Audi’s seats will be hit the spot. You can choose from five modes – Wave, Pulse, Stretch, Lumbar and Shoulder – at three intensities. It feels much more natural than some systems fitted by some rival manufacturers but, be warned, you can be too relaxed.

There is space to spare throughout the cabin, and there’s a huge amount of flexibility in seating and steering wheel positions but, if you prefer to be driven and want to stretch out, there is a long wheelbase version that adds an extra 130mm in the back.

There are plenty of usefully sized cubby holes and storage compartments dotted around the cabin and the option of a cool box and folding tables in the back if you want an office away from the office.

Every version in the A8 range – with the exception of the hybrid – is equipped with Audi’s Quattro four-wheel-drive which means that the A8 is a beguilingly sharp drive with taut boy control and lots, and lots, of grip.

It’s ability as a long-distance cruiser is undeniable and, probably, expected. It is quiet, comfortable and capable of gobbling up the miles without stopping to chew. What’s more surprising is how it handles the tight and twisty back roads. It’s an involving and, for what is a big, heavy car, remarkably lithe and agile.

There are compromises to be made, however, because the low-speed ride is firm and, even with the options provided by Audi’s Drive Select, it’s impossible to find the perfect balance between ride and handling.

The 3,0-litre TDI fitted to my test car, according to Audi’s figures at least, produces 258bhp and will launch the A8 from a standing start to 62mph in 5.9 seconds. What I can tell you is that, in the real world the V6 delivers strong performance right across the range and is insulated well enough that you’d never know – from the inside the car at least – that you’re driving an oil burner.

The boot will hold 520 litres. The opening is wide and the boot is a decent shape so it’s easy to use the space available but, because there’s no split/folding rear bench it lacks flexibility. What you see is what you get.

The Audi A8 is a subtle, understated, but still imposing automobile. It is impeccably constructed and brimming with technology. It’s firm ride and four-wheel-drive ensures that it’s one of the finest handling executive cars and, in spite of its size, it can actually be quite rewarding to throw through some twisty stuff. However, that firm set-up compromises the quality of the low-speed ride. That might be a compromise too far for some potential buyers who prefer to be isolated completely from the outside world but if you prefer to stir the senses every once in a while then the A8 should go to the top of your list.

A8 3.0 TDI quattro Sport 262 PS tiptronic

Price: £66,290

As tested: £73,410

Engine: 3.0-litre V6 diesel

Transmission: 8-speed tiptronic with DSP and sport program

Max power: 262ps @4,000 – 4,250rpm

Max torque: 580Nm @ 1,750 – 2,500rpm

Max speed: 155mph (governed)

Acceleration (0-62mph): 5.9sec

Urban: 39.2mpg

Extra urban: 58.9mpg

Combined: 49.8mpg

Emissions (CO2): 149g/km

For more information visit www.audi.co.uk