Audi A4

Of all Audi's models, the A4 is the one that's probably played the biggest part in making the brand the success story that it is.

At its peak, this was the company's most successful car and by 2019, it still accounted for over a fifth of the German maker's total output.

But by the end of this century's second decade, it was facing ever-stronger challenges in its mid-sized premium executive segment.

Which is why the fifth generation 'B9'-series A4, first launched in 2015, was substantially updated four years on to create the revised model we're going to look at here. Audi has quite a history of providing saloons and Avant estates in this class, stretching back to an Audi 80 model launched as long ago as 1972, which eventually evolved into the first 'B5'-series MK1 Audi A4 of 1994.

Subsequent generations of the A4 model line - the MK2 'B6' version of 2001, the MK3 'B7' version of 2004 and the MK4 'B8' series car of 2008 - firmly established the A4 nameplate in this contender's mainly business-orientated target market.

To the point where, at the time of the launch of this current 'B9'-series MK5 design in 2015, the 80/A4 line had generated over 12 million sales. Not everyone shopping in this sector was a fan.

There were those who sniffed a bit about the fact that, unlike its direct rivals the Mercedes C-Class and the BMW 3 Series, the A4 drove primarily through its front wheels - like a family hatchback.

Others sometimes dismissed it as a plushed-up version of the car that had always shared much of this Audi's engineering, Volkswagen's Passat.

So great efforts were made with the 'B9'-series MK5 model to ensure that this A4 might feel worthy of its price premium, particularly in areas like ride quality, refinement and cabin design.

The result, at the time of the 'B9' model's launch, was a segment benchmark in certain areas.

But by 2019, time had moved on, with all this car's key rivals significantly updated and one in particular, BMW's 3 Series, completely re-designed.

Hence the need for the A4 to re-engage - and the launch in 2019 of this facelifted version of the MK5 model. Quite a lot was new here.

The styling updates might look quite superficial over the original 2015 model but actually, only the roof, bonnet and boot lid of this facelifted version remained the same as before.

Of more significance was the fact that Audi had introduced RDE-1-compliant powerplants and its MHEV mild hybrid engine technology across the range, with a 12-volt system for mainstream models and a 48-volt set-up for the new S4 TDI diesel variant.

Plus on all versions, the cabin gained a new larger MMI infotainment screen to work in concert with the now-standard 'Virtual Cockpit' digital instrument cluster.

There was also more equipment, a revised range structure and some of Audi's choiciest camera-driven safety and autonomous driving technology.

These changes just about sustained the A4 model line to the end of its life in 2024, when it was replaced by a Sportback and Avant estate model range badged 'A5'.

It's always difficult to update someone else's work, but Audi Head of design Marc Lichte addressed the task purposefully with this facelifted version of the 'B9'-series fifth generation A4, leaving only the roof, the bonnet and the boot lid of Wolfgang Egger's original shape untouched.

The previous car was classy, but there was nothing particularly memorable about it.

The saloon and Avant versions of this updated model have a bit more pavement presence. As ever though with an Audi, it's the interior that'll really sell you this car.

In many ways, this remains the defining interior of its class from its era, with cabin quality that's still un-bettered in this segment and the cool, classy feel that's distinctive to this Ingolstadt brand.

The key change here as part of this update was the addition of a much larger 10.1-inch centre-dash infotainment screen, with more sophisticated graphics, acoustic touch functionality and 'natural language voice control'.

Unfortunately, that meant the deletion of the useful rotary controller that had operated the previous MMI system, but navigation was added as standard, as were a wider range of cutting-edge 'Audi connect' media features and standard 'Apple CarPlay'/'Android Auto' smartphone-mirroring.

You're positioned almost faultlessly on supportive heated seats in front of the best digital dash in the segment from this era, the 12.3-inch 'Audi Virtual Cockpit' screen, which from 2019 was fitted as standard throughout the range.

Wherever you look, touch or feel, there are treats.

Buttons click nicely, column stalks feel good and the low-rent plastics you'd find further down in most premium rivals are noticeable by their absence. And in the back? Well in comparison to previous generation A4s, Audi improved the rear passenger compartment of the original version of this fifth generation model by lengthening the wheelbase by 12mm, freeing up 23mm more legroom but that was still only just enough for a tall adult to sit behind an equally lofty driver - and wouldn't be were it not for the scalloped front seat backs.

As for luggage space, well Avant estate models got a standard electrically-operated tailgate and with both body styles, the optional 'Advanced Key' package allows you to open either the boot lid or the hatch by waving your foot below the bumper, should you be approaching your A4 laden down with bags.

This car's conventional mechanism flips the trunk to reveal a 480-litre boot - the Avant estate model would give you 505-litres.

Please contact us for an exact up-to-date valuation.

Most owners in our survey seemed happy.

We've heard of gearbox problems, seat backrest faults and suspension issues, so check all these on your test drive.

The steering rack can experience electrical and mechanical failure and might be noisy too.

The most reported faults related to interior trim and non-engine electricals.

Look out for bodywork scrapes and kerb damage to the large alloys.

We've had some reports of issues with wear to the side bolsters of the leather seats, as well as squeaking front brake pads, so it's worth looking out for both of those.

There were a few issues with the car's infotainment system, with phones not connecting properly and flickering screens being the main problem.

Rattling parcel shelves and buzzing interior trims were also reported.

The DSG automatic gearbox should be checked to make sure it's had a regular oil and filter change, as should the quattro four-wheel-drive system. Many A4s will have been company or lease cars and, as a result, you should check the condition of the bodywork carefully.

The high-quality fit and finish of an A4 also makes it an ideal candidate for clocking, so ensure the history is absolutely verified.

As for manufacturer recalls on the A4, well some A4 models built in March 2019 may have problems with a shock absorber fork.

(approx based on an A4 2019 30 TDI - Ex Vat - autodoc.co.uk) An oil filter costs in the £4-£15 bracket.

An air filter's in the £13-£20 bracket.

Front brake pads sit in the £28 to £71 bracket for a set; for a rear set, it's around £20-£43.

Front brake discs sit in the £41-£78 bracket; for a rear pair, you're looking at around £40-£65.

Starter motor prices vary widely - from £55-£413, depending on brand.

As do costs for an alternator (anywhere in the £186-£687 bracket we found).

In terms of what was changed here as part of this B9 model facelift, the key thing was Audi's adoption of mild hybrid engine technology almost right across the board, with a 12-volt MHEV set-up provided for virtually all the brand's four cylinder engines.

Otherwise, the engineering of this MK5 A4 remained much as it had been when we first saw it back in 2015 - which meant it was still primarily a front or four-wheel drive car; in a segment dominated by rear-driven rivals.

This hadn't held this Audi back too much in the past and the brand didn't expect that to be much of an issue with this facelifted fifth generation 'B9'-series model either.

Potential buyers of this car tend to prioritise comfort and refinement rather than on-the-limit handling and in this form, the A4 continued to deliver impressively in both of these areas.

The only real caveat here lay with the firmer Sport suspension customers had to have with the 'S line' trim level that most of them chose.

Try before you buy is our advice. We mentioned the mild hybrid engine tech.

The only powerplant that didn't get it was the older-tech 2.0-litre diesel unit fitted to the 40 TDI quattro derivative, a 190PS model.

Otherwise, the MHEV system featured on all the four cylinder powerplants, incorporating an integrated 'BAS' belt alternator starter-generator that powered a 12-volt main electrical set-up in which a compact lithium-ion battery in the boot stored energy harvested via a 'KERS' kinetic energy recovery system.

A strong seller was the entry-level A4 35 TFSI petrol variant, which in this updated form got a 150PS 2.0 TFSI unit and was (from launch) the only model in the range that could be had with a manual gearbox.

In S tronic auto form, an A4 35 TFSI is capable of 42.8mpg on the WLTP combined cycle.

The same 2.0 TFSI engine was offered in 190PS form in the 40 TFSI - and in 245PS guise in the 45 TFSI quattro.

Diesel buyers were offered the Volkswagen Group's uprated 2.0 TDI unit in 136PS form in the base 30 TDI derivative, or in 163PS guise in the mid-range 35 TDI model many A4 customers will still want.

Diesel also powered the sporting S4 model, which initially used a 347PS 3.0-litre twin turbo six cylinder unit, which had the more advanced 48-volt MHEV system and is boosted by an electric compressor.

This was replaced by a 3.0-litre petrol turbo V6 in 2020.

By 2019, Audi had spent nearly a quarter of a century perfecting its A4 - and that really shows in the improved version of the fifth generation model.

It's a spacious, classy car that's very composed to drive and is fully conversant with the kind of hi-tech design and faultless cabin quality that its target junior executive market likes to expect.

So it stacks up in the showroom just as well as it does on the balance sheet, with running cost returns that should please your company accountant.

Audi knew this car's front wheel drive / quattro 4WD drivetrain format wasn't going to make it the segment choice for handling response, but did get surprisingly close to the standards established in this regard by BMW and Mercedes.

At the same time, Ingolstadt concentrated on perfecting refinement and ride quality, with the result that both remain difficult to better in this class. And in summary? Well, even more than before, in this form this A4 feels like a car that's been lovingly and very carefully considered.

The depth of engineering and the thought that went into the tiniest details combine to further enhance the warm fuzzy feeling that's charmed Audi customers for years.

If you're one of those people, then you'll like this car very much.

And even if you're not, you'll find it hard not to be impressed by way it systematically ticks almost every box on the mid-sized executive market wish list.

It's very thorough.

And very Audi.