What Car? says...
The Audi S4 is a great example of a blisteringly quick performance car with understated looks. Like Clark Kent before he whips off his glasses to become Superman, it has heroic performance while remaining almost invisible to those not in the know.
The S4 sits on the middle step of the Audi A4 range, above the regular model but below the even faster Audi RS4 Avant. It aims to strike a good balance between the two, taking elements from both to be a usable daily driver but with plenty of performance.
A little unusually these days, the S4 runs on diesel, with a 3.0-litre V6 bi-turbo engine under the bonnet. That's aided by a hybrid system that delivers a total of 345bhp.
As such, where the RS4 is a match for the very hot BMW M3 and Mercedes-AMG C63, the S4 is more traditionally a rival to the Mercedes-AMG C43. Don’t start thinking that the performance comes at the expense of practicality though – like the C43, the S4 can be had as either a saloon or estate (called the Avant by Audi).
Over the next few pages, we’ll put the Audi S4 up against the alternatives in key areas such as performance, practicality and comfort, to find out whether it has done enough to sway your decision.
Then, once you’ve made your choice, don’t forget to take a look at the free What Car? New Car Deals pages to see how much you could save on your next new car without any of the awkward haggling. You’ll find some new performance car deals.
Performance & drive
What it’s like to drive, and how quiet it is
The fact that the Audi S4 wields a 3.0-litre V6 bi-turbo diesel engine might sound like it’s a bit out of touch, but it makes use of sophisticated technology to keep it as clean as possible. Much of that hinges on a 48-volt electrical system that powers an electric compressor (basically a turbocharger driven by an electric motor), which works with a regular turbocharger to make 345bhp and 516lb ft of shove.
All that power is available from just 1,500rpm, making the S4 more flexible as well as quicker to 62mph (the official time is 4.6sec) than the Alfa Romeo Giulia Veloce and Jaguar XE P300. In fact, it would be even more effortless to drive than the Mercedes-AMG C43 except for one thing – the incredibly laggy and unresponsive automatic gearbox.
There's a noticeable delay when you put your foot down that's frustrating when you're diving for traffic gaps on a roundabout, and the S4 lurches forward with a sharp jolt when the power does kick in. Thankfully, that hesitance can be reduced by knocking the gearbox into its Sport setting, or using the paddles mounted on the steering wheel for much smoother transitions between gears.
There's an electronic sound-generator (read: fake exhaust sound), so despite running on diesel, the S4 sounds more like a petrol V8. The exhaust note is much meatier than the four-cylinder engines of the Giulia and XE, and it's easy to appreciate because there's not a lot of wind and road noise.
As with the XE and C43, all the grunt is managed reassuringly by the standard-fit four-wheel drive. As a result, the S4 feels quick and stable whether the road is wet or dry. It’s so well balanced, you find yourself maintaining grip around corners without any effort, and the steering is nicely weighted to inspire confidence. It’s not the best-handling performance car of its kind, though: the Giulia Veloce and XE steer even more sweetly.
You get passive suspension as standard, while the top-spec S4 Vorsprung has an adaptive set-up with several driving modes, allowing you to relax or stiffen up the car. In its softest Comfort setting, the ride is composed on a motorway and supple enough around town.
The interior layout, fit and finish
To differentiate the S4 from a regular Audi A4 it has a darker colour scheme with a black roof liner and plenty of carbonfibre and Alcantara – or if you want a more lively look you can opt for bright red seat upholstery. Everything you touch feels expensive enough to be in a car of this price – even the feel of pressing the buttons feels a cut above most executive cars.
Napa leather graces the S4's seats, which are more supportive than in the standard car, and hold you in place firmly during quick cornering. They’re electrically adjustable, with four-way lumbar support and even a massage feature to soothe you on long journeys.
Every S4 gets a 10.1in infotainment screen which you control by touch, rather than the physical controls on previous models. The sheer amount of information it can display at any given time can be hard to register when you can only spare a glance when driving. Making selections on the move by touch isn't as intuitive as using the rotary controller that's a feature of BMW's iDrive system in the BMW 3 Series.
To help dilute this information overload, all S4 models get a 12.3in digital driver's display in place of a traditional analogue speedo and rev counter. Called the Virtual Cockpit, the configurable screen can show full-screen sat-nav maps and other information. The S4 also gets a specific ‘S’ arrangement for the screen, dominated by a big central rev-counter, a bit like in the Audi R8 supercar.
Passenger & boot space
How it copes with people and clutter
The S4 is, not surprisingly, very similar to any other Audi A4 in terms of space and practicality. There's plenty of space up front for two to sit without clashing elbows, divided by a wide arm rest in the middle. The car's width makes it more comfortable than the Mercedes-AMG C43 for rear-seat passengers – you can carry three adults in the back of an S4 for longer before they’ll start complaining.
The boot in the S4 – in both the saloon and Avant – is the same as that of the A4, and more convenient to use than that of the C43 because of its squarer shape. There’s plenty of space for a set of golf clubs or the weekly shopping without having to fold the rear seats down.
As with most direct rivals, the rear seats can be split in a handy 40/20/40 layout, making it easy to store long loads. What’s more, all S4 models get handy netted storage areas on either side of the load area.
Interior storage space is no different to the A4. You get a large stowage area under the front armrest, two cup holders in front of the gear selector and sizeable door bins that can each hold a 1.0-litre bottle.
Buying & owning
Everyday costs, plus how reliable and safe it is
The most affordable Audi S4 looks pretty competitive price-wise next to the Alfa Romeo Giulia Veloce and will cost you far less than the entry-level Mercedes-AMG C43. While you’ll have to opt for the top-of-the-range S4 Vorsprung to match the C43’s standard-fit adaptive suspension, that will still work out cheaper.
Better still, the standard S4 gets heaps of equipment, including 19in alloy wheels, a rear-view camera, LED signature headlights, sports seats and a touchscreen infotainment system.
The mid-range Black Edition looks smart, with extra black detailing inside and out, but doesn't add any extra kit, while the top-spec Vorsprung comes with pretty much every feature shown in the Audi brochure. You get a panoramic sunroof, heated front and rear seats, a Bang & Olufsen sound system, matrix LED headlights, hands-free boot opening and the Parking Assistance Advanced Pack with 360-degree parking camera and park assist. It adds thousands to the price, though.
On the other hand, stepping up from a top-spec 187bhp A4 40 TDI Vorsprung to a well-equipped standard S4 is a relatively small financial leap to make, and could be worth it for the power of that big diesel engine. You can expect the diesel S4 to be more economical than the petrol C43, but both will costs a lot as company cars because of their high tax rates.
Private owners may find that the S4 is a tad cheaper to service than the C43, but it isn’t predicted to hold its value as well over three years. Of course, the difference in initial outlay somewhat negates that advantage here.
In terms of reliability, the S4 wasn’t included in the 2022 What Car? Reliability Survey but the Audi A4 finished near the bottom of the executive car class, just below the Mercedes C-Class. Audi beat Mercedes and Alfa Romeo in the manufacturer table, coming 21st out of 32 brands included.
Every S4 comes with a three-year, 60,000-mile warranty, which is fairly standard among performance cars. The Giulia Veloce and C43 get three years but with unlimited mileage.
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