A big, elegant luxury saloon, the Audi A8 uses aluminium to keep weight down and yield an advantage over heftier rivals. Highlights include the interior build quality, quattro four-wheel drive mechanicals and air-suspension but there's also the exemplary refinement and advanced engine technology to factor in. The 2.8-litre FSI petrol engine gives surprisingly reasonable economy and emissions while the 5.2-litre V10 S8 turns in savage performance but pick of the bunch is the 3.0-litre TDI diesel.

Being lightweight isn't something one usually associates with full-size luxury saloons. In this rarefied sector of the market, weight is one of many things that the major protagonists have a surfeit of. All that technology and equipment, those luxurious materials and the build quality that marries it all together: this is how the luxury saloon justifies those big price tags and none of it tends to be particularly light. Things are changing though. The environment has never been a bigger issue and the green lobby's tentacles of influence are stretching even into the blue-blooded realm of the luxury saloon. These days, company directors and chairmen of the board need to be green or at least to be seen to be being green and the aluminium bodied Audi A8 is better placed than most to oblige them.

The A8's aluminium architecture has a big influence on the way the car rides and handles. The Audi is around 100kg lighter than an equivalent BMW 7 Series, even with the Quattro four-wheel-drive mechanicals installed, and saves over 200kg compared to a Mercedes-S-Class which, like the BMW, is rear-wheel-drive. These don't sound like massive differences in a 1,800kg car but it's the equivalent of a couple of portly passengers and the A8's lightness helps it achieve a responsiveness and poise on the road and means the engines have an easier time of it. The range now opens with a 207bhp 2.8-litre V6 FSI unit that employs Audi's latest valvelift technology to boost efficiency and performance. Next comes the 256bhp 3.2-litre FSI engine which is also a V6 and the 4.2-litre V8 with its 345bhp output. The 444bhp W12 engine tops the standard range and diesel customers can select either the 3.0-litre TDI or the 4.2-litre TDI that produce 230bhp and 322bhp respectively. All of which leaves only the barnstorming S8 performance model with its Lamborghini-sourced 5.2-litre V10 engine and 444bhp.

"The A8 is at its most impressive when taking things easy?"

The A8 is extremely refined at cruising speeds with the engines only breaking into a low roar when extended and the standard air-suspension creating a luxurious magic carpet effect. The latest models also benefit from revised rack and pinion speed-sensitive steering for improved feel at the helm. The smaller petrol engines are available in front-wheel-drive form to help with economy but further up the range, it's an all-quattro affair for biting traction even in slippery road conditions. The tiptronic gearbox is smooth in operation and can operate in fully-automatic mode or as a clutchless manual via the wheel-mounted paddle shifters. Audi also offers the Multitronic CVT gearbox with the V6 petrol units which can actually improve fuel economy.

The A8 is at its most impressive when taking things easy but it can certainly pick up its heels when required. 0-60mph performance times range from 8.0s in the 2.8-litre V6 equipped car to 6.1s in the V8 diesel and 5.1s in the awesome S8. Top speeds are artificially capped at 155mph in all except the 3.0-litre TDI which runs out of steam at 151mph.

The A8 has a real aura of class about it. The long body and high window line give the car a low, ground-hugging stance that combines with the imposing front end to give it plenty of road presence. The look is still pleasantly understated compared to its big saloon rivals, however, the Audi coming across as a more elegant alternative in a sector populated by overt status symbols. The current model benefits from a smarter design for the trademark single frame grille, LED indicator strips in the side mirrors and LED tail lights.

The interior is a masterclass of Audi design. The A8 flagship was the first car to trial many of the features and themes that have since been rolled out across the marque's model range. Well judged use of chrome detailing, high quality plastics and the class leading MMI control interface give the A8's cabin a degree of style and usability that rivals struggle to emulate. The controls are a pleasure to use from the switch for the electronic handbrake to the dial that controls the headlights: it's all solid feeling and beautifully weighted. Even in the standard wheelbase models give abundant rear legroom and as the sleek, elongated styling suggests, there's a massive boot out back. This is simply a great place to sit out a long journey, whether you're behind the wheel or luxuriating in the rear with your chauffer doing the hard work.

Equipment provision is at a level befitting this prestigious sector of the market. All A8 customers find themselves in possession of a 9-speaker 230-watt stereo with a six-CD auto-changer and a DAB digital radio. There's four-zone climate control so that each occupant can adjust the temperature as required, heated front seats and full Bluetooth mobile phone compatibility. Prices range from £49,995 up to £80,995 and there's a choice of SE or Sport trim levels with the latter adding sports seating in two-tone leather along with the sports steering wheel and bootlid spoiler seen on the S8.

The possibility is always there to trawl through the options list and have your A8 delivered with a technology quota to rival your local branch of PC World. One item that stands out is the Audi side assist and lane assist system. It uses radar technology to detect vehicles in the A8's blind spot, alerting the driver by illuminating an LED in the wing mirror. If the driver then indicates to change lanes on that side, the warning LED grows brighter and flashes to attract the driver's attention. Also part of this technology is the lane assist function that uses a small camera to detect the lane markings and sends a warning vibration through the steering wheel if the driver starts to drift across a line without indicating.

The A8's lightweight aluminium construction gives it obvious advantages over bulkier rivals in terms of accelerating, braking and handling but in the increasingly green-aware automotive marketplace, the marque is also keen to emphasise its environmental credentials. The entry-level 2.8-litre engine is at the centre of this eco-drive on Audi's part. Its valvelift technology in combination with the FSI injection system can adapt various parameters of the combustion process to optimise either performance or economy according to the throttle loads that the driver is applying. It's capable of 34mpg on the combined cycle and 199g/km CO2 emissions which is better than Hybrid models like the Lexus LS600h and even diesels such as BMW's 730d.

Audi's own diesel engines give an appealing compromise between muscular performance and economy with the 3.0 TDI capable of 33mpg and 224g/km but as you ascend the range, the more powerful engines prove less cost-effective. You'll certainly be lucky to achieve the official 21mpg from the S8 if you regularly access its blistering performance and its 319g/km emissions won't get you an honorary membership of Greenpeace.

Depreciation in this sector is traditionally severe, especially where the more expensive big-engined models are concerned, but buyers with the means and the inclination to buy an A8 won't be unduly concerned by this or the prohibitive insurance costs.

Alan Sugar famously likes to deride his apprentices by branding them 'lightweights' before his inevitable 'you're fired' coup de grace. Audi, however, is confident that the aluminium construction and resultant light weight of the A8 luxury saloon will get the car hired by the high-flyers of British businesses. Luxury saloons have long been the epitome of automotive excess but by keeping its mass low, the A8 manages impressive performance and handling and can also play the increasingly important green card very effectively, helped by some advanced engine technology.

With sleek looks, first rate refinement, a great array of engines and an interior that showcases Audi's design expertise in outstanding fashion, the A8 has all the attributes it needs to succeed. It may be less ostentatious than its German rivals but this understated approach has been serving Audi well in its battles with BMW and Mercedes over recent years and that looks set to continue here.

TOP 2 A8 DEALS

The results below show the top A8 deals on buyacar

	Audi A8 3.0 TDI Quattro SE LWB 4dr [Non-DPF] Tip Auto Saloon
	ETR	Mthly	Saving £7,170	Price £47,200
	Audi A8 3.0 TDI Quattro Sport LWB 4dr [Non-DPF] Tip Auto Saloon
	ETR	Mthly	Saving £7,611	Price £49,909