Audi A8 [D5] (2017 - 2021) used car review

Brilliant breakdown + serious savings

Brilliant breakdown + serious savings

Breakdown cover from just £7.95 a month*. Plus up to £150 of driving savings!

Brilliant breakdown + serious savings

By Jonathan Crouch


In fourth generation form 'D5'-series form, Audi's A8 became smarter, more efficient and ground-breaking in its use of autonomous driving technology. In this pre-facelifted model's 2017-2021 sales period, models from better established badges in this sector may be tempting, but they can't offer many of the almost unique things this car brought to the full-sized Luxury saloon segment: mild hybrid engine electrification, all-wheel steering and for most models, an active suspension system are just a few examples. In short, there ought to be enough here to please the most demanding boardroom buyer.


4dr Saloon (3.0 TFSI petrol / 4.0 TFSI petrol / 6.0 TFSI petrol / 3.0 TDI diesel / 4.0 TDI))


The 'D5'-series fourth generation Audi A8 claimed to usher in a new era of sophistication, not only for its brand but for the industry as a whole. Vorsprung Durch Teknic - 'Advancement through technology' ? Remember that? It was once the mantra that dictated everything Audi did, originated back in the Eighties to describe the company's 100 and 200-series models that really were the most advanced executive contenders of their time. The car that really epitomised this philosophy though, arrived shortly afterwards, the first generation version of this A8 model, launched back in 1994. Things like aluminium space frame construction, double-glazed windows and an LED driver information display really were ground-breaking back then and that original A8 had them all, instantly making its Mercedes S-Class and BMW 7 Series rivals look out-of-touch and behind the game. It's that kind of segment leadership that this MK4 model aimed to re-establish at its launch in 2017.

It had to do that because the second and third generation versions of this car, launched respectively in 2003 and 2010, didn't really pick up that predecessor model's technological gauntlet. Aside from quattro 4WD, they offered boardroom buyers little they couldn't get elsewhere in the full-Luxury saloon sector and by the middle of the 21st century's second decade, Audi had slipped back not only behind Mercedes and BMW but also behind brands like Lexus, Jaguar and even Tesla in the segment pecking order. A giant step forward was needed for this MK4 A8.

At launch, it was - according to its maker - a car with a greater capacity for autonomous driving than any other in the world, integrated 'Audi AI' technologies able to allow its user not only to relinquish control at certain speeds but actually to engage in other tasks unconnected with driving. But that was just the start. The petrol and diesel engines used became much more efficient thanks to 'MHEV' mild hybrid electrification and the new-era cabin was completely touchscreen-orientated. Sleek exterior styling introduced a fresh design language for the brand and clothed a body structure fashioned from a hi-tech mix of aluminium, steel, magnesium and carbon-fibre-reinforced plastic. Plus options included four-wheel steering and an astonishingly sophisticated active air suspension system. In short, it was Vorsprung Durch Teknic to the max.

Audi introduced a PHEV version, the 60 TFSIe, shortly after launch. Then subtly updated the car in early 2022. It's the earlier 2017-2021-era versions of this 'D5'-series A8 though, that we look at here.

What You Get

Twenty years ago, this is a piece of styling we'd have been gasping over, a progressive and sophisticated vision of how the monied elite would travel in the 21st century's third decade. Today, we're a little more used to futuristic styling statements of this sort but the fourth generation 'D5'-series A8 still looks technically advanced and comfortably of its time, handsome and imposing, if not classically elegant. Stylist Mark Lichte said it ushered in a whole new era of design or the brand. Size matters in this segment, so the A8 in this form became larger still, as you can appreciate from a profile perspective. Even the standard version is 5.17-metres in length, 37mm longer than before, while its long wheelbase stablemate put on 130mm to better justify its entry-level limousine status.

Behind the wheel, the Vorsprung Durch Teknic charisma of this car really gets into gear. There's a different, more technological ambiance than you get with obvious rivals from this period, but the interior still incorporates the required splash of elegance needed for a car of this status. You're going to need to like screens because the cabin incorporates no fewer than three of them, largely replacing all the many buttons and dials of the previous model. The two you'll notice first power up as soon as the door is opened and dominate the upper and lower parts of the piano black-trimmed centre stack. The gently curved upper 10.1-inch display deals with the most important radio, media and telephone functions while the lower 8.6-inch monitor is reserved for more comfort-orientated mainly climate-related features. Both monitors interact with the configurable 12.3-inch 'Audi Virtual Cockpit' instrument binnacle screen you view through the four-spoke wheel.

At the rear, what you'll find depends upon which of the rear seat packages has been fitted to the model you're looking at. Standard models get a conventional three-person rear bench, but if you've gone for the long wheelbase body style, it's quite likely that you'll want an A8 fitted with one of the optional 'Rear Seat Packs' that give you two individual seats separated by a leather-covered centre console. Even with the standard body style and the conventional rear bench layout, it can all be made to feel pretty plush. That's if you add in long wheelbase model features like sun blinds, powered heated seat adjustment, 4-zone automatic air conditioning and luxurious 'Comfort' headrests trimmed in soft, velvety 'Cocoon' leather.

The boot lid rises electrically and can do so with a wave of your foot beneath the bumper, should your chauffeur have taken the day off and you've found yourself approaching the car laden down with bags. We expected trunk space to have increased with the extra body length of this MK4 model, but actually it shrank from 520 to 505-litres. That's a fraction less than you'd get from Mercedes and BMW rivals of the period, but it's still enough to take up to eight carry-on suitcases and of course a couple of golf bags are easily accommodated.

The under-floor space is entirely taken up by the spare wheel, but you get a floor net that can be strung between chromed tie-down hooks. And there's a small netted area on the left. If you're likely to be often carrying longer items like skis, you'll need to get a car whose original owner paid extra for the optional ski hatch. If you need more room for bigger items and you've got an A8 with a rear bench rather than two individual rear chairs, there's the useful fold-down backrest that you'd have to do without in a rival Mercedes S-Class or BMW 7 Series.

What You Pay

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What to Look For

Most owners in our survey seemed happy. A few needed software updates; one had a rear turn signal malfunction (apparently a common issue). Make sure no error messages come up on the dash when you start the car, especially if they stay on. And be wary of any models with air suspension problems, which will be pricey to sort. Check that's system's operation. And allow plenty of time to go through the functions on all the various screens.

Check that the various recall issues have been attended to. One for shock absorbers (models made October-December 2018); one for front passenger seat rails (models made January-March 2019); one for a gearbox oil leak (models made September-December 29019); and one for an issue with the active headrests (models made January 2018). As usual with this kind of car, check the big wheels for signs of kerbing. And obviously insist on a full service history.

Replacement Parts

(approx based on an A8 50 TDI (2018) - Ex Vat) An oil filter costs around £6. A fuel filter is around £27. Front brake pads sit in the £61 to £100 bracket for a set; for a rear set, it's around £25-£63. Front brake discs sit in the £130 bracket; for a rear pair, you're looking at around £100-£185. A pollen filter costs in the £6-£34 bracket. And a wiper blade is around £17-£20.

On the Road

At first glance, this fourth generation A8 certainly seems to have plenty in its armoury. It rides on the same super-sophisticated 'MLB evo' platform used by the Porsche and Bentley models of the period: it was the first model in its segment to offer a combination of four wheel drive and four wheel steering; and it was the only car in the class in its time that in some mainstream guises could offer an air suspension system able to be embellished with predictive active technology that reads and reacts to the road ahead. The engines were sophisticated too, the mainstream 3.0-litre V6 turbo units both fitted with MHEV mild hybrid technology. There was a 340PS '55 TFSI petrol' derivative that also donated its engine to an additional 462PS Plug-in Hybrid variant, but most buyers will want to stick with the 286PS '50 TDI' diesel derivative. Primarily because of economy that sees up to 50.4mpg being possible on the combined cycle and up to 145g/km of CO2. If you're less worried about efficiency, there was also a 435PS V8 TDI diesel, a 453PS V8 petrol variant and a petrol-powered 6.0-litre W12 flagship model but all these are vanishingly rare on the used market.

All the engines are mated to tiptronic auto transmission and quattro 4WD. Along with a much stiffer structure that helps the car feel far more planted through the bends should the need arise for you to push things along. This fourth generation A8 model's real calling card though, is its emphasis on autonomous driving technology. Whether a model primarily aimed at chauffeurs and private hire drivers should be prioritising that is perhaps debateable, but this A8 did so anyway, pioneering the so-called 'Level 3' technology that allows the driver to fully relinquish control on certain roads at certain speeds. The so-called 'Traffic Jam Pilot' system original customers could specify on this car only allows that facility on properly divided highways at speeds of under 37mph but in operation, it's undeniably impressive, as are the associated 'Parking Pilot' and 'Garage Pilot' systems that were fitted to some models and could allow you to remotely park your car when you reach your destination.


Audi built its reputation on technology, then fell back on stylistic design and cool marketing to sell its products. This fourth generation 'D5'-series A8 signalled a welcome change of direction - a reversion back to the company's core principles, offering things you simply can't get elsewhere. If it feels more advanced than its period rivals from behind the wheel, that's because it is. Of course, there are always going to be those who'll prefer the heritage and elegance of a Mercedes S-Class. Or the slightly more dynamic demeanour of a BMW 7 Series. We also think that both of these rivals make a slightly more distinctively upper-class statement - though you may disagree.

The whole point though, is that an A8 ought to be a more futuristically modern boardroom conveyance - which is the kind of experience this MK4 model sets out to offer. Whatever your perspective, it's a formidable Luxury segment contender and a fitting showcase for Audi's most advanced engineering. Hugely capable, innovative and beautifully built, this is the car that rivals always feared Audi would build. And if you're in this market for a boardroom level large luxury saloon from the 2017-2021 period, it's one you need to try.

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