The exterior design of the RS4 has always been about blending just the right amount of discretion and purpose. It's the sort of car that gets a nod of appreciation from those who know what it is but is low key enough to pass unnoticed most of the time. Under the skin is Audi's MLP platform, that which underpins the RS5 coupe that shares this car's V8 engine but lacks its near perfect weight distribution. As for the stuff you can see, well, this car sits 20mm lower than a standard A4 Avant and is 20mm longer and 24mm wider. Chiselled sill extensions and gently flared wheel arches hint at the performance potential, while unique bumpers, a matte aluminium-style front grille and silver mirror housings are all 'RS' sub-brand giveaways to those in the know, as is the smart roof spoiler. Twin oval tailpipe caps and a small diffuser are visible from the back of the car, which is the view most other drivers will get of the RS4.
While there's a decent colour choice for the paintwork, the interior is almost totally black, unless, as we would advise, you find a car with the optional Moon Silver headlining. Otherwise, there's little to break up the cabin darkness apart from chrome clasps on the switchgear and carbon inlays. Sporting cues include a flat-bottomed leather multifunction sports steering wheel with aluminium-effect shift paddles and brilliant power adjustable Super sports seats, covered in a combination of leather and Alcantara. We'd still be tempted to go for a car fitted with the optional race-style bucket seats though. Pedals, door sill trims and air vents also mirror the aluminium look, while the instrument cluster bezel is trimmed in contrasting piano black. It all feels agreeably expensive. Nobody does this stuff quite like Audi.
In the rear, while there's comfortable space for two, a third adult would sit less happily on longer trips. But there's certainly enough space for five people's luggage though, with a 490-litre boot that can be extended to 1,430-litres if need be. Even Superman needed to put a business suit on at times.
Reliability isn't generally an issue for the RS4. You'll hear lots of horror stories regarding the engine problems experienced with the previous generation version, but these had generally been ironed out by the time of this post-2012 model. Engage the seller in dialogue and try and find out whether the car's been used on trackdays: if it has, we'd walk away. Look out for kerbed alloys - they can be pricey to fix. Have the brakes checked as well; the car in question might need new pads/rotors. Otherwise, provide the car has a fully stamped-up history, you can buy with relative confidence.
(approx based on a 2012 RS4) Brake pads are between £45-£55 for cheap brands and between £45 and £50 if you want an expensive make. An ABS sensor sits in the £40 to £55 bracket. A drive belt is around £16. Oil filters cost around £25. Wiper blades cost £10-£30, depending on the brand you choose. An air conditioning condenser is around £145.
Not a lot prepares you for just how quick this car really is. Certainly not the initial experience of getting in - and firing the thing up. Yes, there are brilliant 'batwing' sports seats but otherwise, at first glance, it's pretty much standard high-end Audi. And yes, a prod of the 'Start' button produces a satisfying V8 whuffle, but nothing to suggest that you'll be shortly worrying Ferrari folk. But then subtlety, you might think, is all part and parcel of the RS4 experience. And we'd agree up to a point. Except that there's nothing really very subtle about the behaviour you have to adopt to get this car to really deliver in the way that you just know it can.
Here's a machine that just loves to be picked up by the scruff of the neck and given one hundred per cent, at which point you get a fuller acoustic repertoire of pops, yowls, rumbles and barks than anything else this side of a proper supercar, enough to paint a very big smile on your face. Audis don't normally do this. You admire them, but they don't send the hairs on the back of your neck upright. Which makes this RS4 something very special.
Especially when you're hurling it away from rest. Yes, you can ease this car into the traffic like an A8, which with this MK3 model was easier than ever to do thanks to the provision of a silky-smooth 7-speed S tronic auto twin-clutch transmission to replace the previous manual 'box. Once in a while though - and you simply have to try this if you buy this car - find yourself a clear space of road and try it DTM-style. There are no fiddly settings for the standard Launch Control: you simply disengage the stability system and select 'Sport' mode on the gearbox. Then apply left foot to the brake with right foot planted on the accelerator. The engine holds revs at about 3,000rpm and you get a dramatic World Rally Car soundtrack. Then sidestep the brakes and hang on.
It's just brutal yet hugely addictive and your local Audi centre won't take kindly to you doing it on the test drive. It's barely any slower in the wet, conditions in which rival rear-driven BMW M3 or Mercedes C63 AMG models would be slewing their way through the puddles, traction control lights flashing like belisha beacons. In contrast, the RS4 just grips and goes.
Under the bonnet lies what appears to be the same 4.2-litre V8 that was fitted to the previous generation version of this car, a surprise for Audi followers who in 2012, expected either an uprated version of the supercharged 3.0-litre V6 fitted to the S4. Or, perhaps more likely, the twin turbo V8 developed for Ingolstadt's S8 super saloon and borrowed by Bentley's Continental GT. Instead, the brand decided with this MK3 model to give this classic 4.2 V8 one last outing before the green lobby put the final nail in its coffin. And what an engine it is, also used in the brand's RS5 coupe and convertible and, as there, offering glorious aural fireworks under heavy acceleration that sees 62mph flash by from rest in the same 4.7s increment as before on the way to a top speed that can be as high as 174mph if you find a car where the original owner paid extra to have the 155mph restrictor removed. We probably need to put those stats into perspective. Take, for example, the kind of supercar you maybe had on your bedroom wall as a kid - say a Ferrari 512TR. Yes, this eminently practical family five-seater is just as fast.
So much though was also true of this car's direct 2006 predecessor - and at least that car could be had with the manual gearbox that most enthusiasts prefer. So where's the progress? Well bear with us - we're getting to that. For a start, Audi's engineering division won't be happy with us at all for suggesting that this car's engine is essentially unchanged because actually, they put an awful lot of work into trying to improve it. You don't achieve efficiency improvements of up to 30% without changing virtually every part, yet was done at the same time as pushing up peak power from 420 to 450PS and offering the driver the chance to exploit it all 1,500rpm further down in the rev range, from a much more accessible 4,000rpm.
Anyway, even if the engine hadn't changed, the fundamentals of this design very did in MK3 guise. Fed up with hearing BMW boffins drone on about how much better their cars are thanks to their even 50/50 front-to-rear weight distribution, the Ingolstadt engineers achieved pretty much the same thing here by shoving 90kgs of the engine's mass backwards which, as you might imagine, results in a notably sharper front end. Along with a revised quattro 4WD system that now in normal conditions pushes only 40% of power towards the front, it helps to create the more rearward-biased feeling of control that driving connoisseurs prefer. Safe in the knowledge that should conditions or over-enthusiasm lead to trouble, the ratio can change in milliseconds, either with up to 70% of power directed to the front or up to 85% directed back to the rear.
In extremis, you won't really feel any of this happening, even if you had time to. All you actually experience are flattering feelings of Schumacher-like control and seemingly limitless grip, further enhanced by a torque vectoring system that helps get all that power onto the tarmac through tight turns, working with a self-locking crown gear differential system and a Sports rear differential for exceptionally smooth torque transfer between the front and rear axles and the left and right rear wheels. Plus there's an Electronic Stability Control system that offers a 'Sport' mode or can be deactivated completely for circuit use.
Before driving like this, you'll have chosen your transmission mode (either 'Drive'. 'Sport' or 'Manual') and, most importantly, you'll also have visited the 'drive select' system familiar from humbler Audi models, a set-up there for the tweaking of steering weights, gearshift patterns, plus throttle and steering response (and in this case the operating characteristics of the Sport differential too). Then you'll have switched your 'drive select' setting away from either 'Auto' or 'Comfort' and onto either 'Dynamic' (which introduces a pleasingly throatier exhaust note and delicious gearbox downchange throttleblips) or the 'Individual' setting that allows you to set up this RS4 exactly as a real pro would set up his racecar.
The 'drive select' system becomes even more of a 'one-stop-shop' for 'red mist' mode if, as we would suggest, you specify the 'Sport Package' that 80% of original owners chose. The various settings then also tweak the ride (via a clever Dynamic Ride Control system that reduces bodyroll through the corners) and can have a more direct impact on the steering (through an 'active' variable-ratio Dynamic Steering set-up that still doesn't deliver as much steering feel as we would ideally like but is much better than the standard set-up). In other words, you can get on your favourite country road, hit 'dynamic' on 'drive select' and instantly get the steering, ride, gearshift and throttle response exactly as you want it. Brilliant.
Find a car fitted with the optional 'Sport Package' and you also get larger 20-inch wheels (gorgeous-looking but frighteningly easy to kerb) and something we'd just have to have if we owned this car, a sports exhaust system to emphasise the V8's distinctive engine note. You may also find a car fitted with the pricey optional carbon ceramic braking set-up. Mind you, to get the benefit of that on a public road, you'd have to be driving so fast that you might just as well stop by the local police station and give yourself up.
Ultimately, what it boils down to is that this RS4 will ride well, steer cleanly, grip like you wouldn't believe and just demolish any give-or-take road in any weather. No wonder it's in a class of one.
Never mind the R8 supercar or the TT coupe, if you want to understand how brilliant Audi can be in building a sporting car, the RS4 is always the best barometer, especially in this third generation guise. With 450PS from a hand built 4.2-litre V8 that revs to 8,250rpm, it's obviously fast, but thanks to clever electronics, optimised weight distribution and a more rear-driven agenda, this generation version puts something on the menu that's sometimes been absent from Audi RS models: fun.
Is it perfect? No of course it isn't. The steering lacks a little feedback, the fuel tank is too small to match the engine's thirst and we can't afford one. Other than that, it's virtually flawless, which is impressive as it doesn't really have to be. After all, what other high-performance four-wheel drive estate car is there to challenge this one? An AMG Mercedes or an M Power BMW from this era wouldn't give you the all-round grip. A high performance SUV couldn't offer the pin-sharp handling.
Perhaps this MK3 RS4 needed to be this good to continue deterring rivals from making a challenge. Who knows? What's beyond debate is that if you love fast cars and need something with more than a little practicality and year-round capability, then this Audi stands head and shoulders above anything else remotely comparable. Drive it and you'll experience a slightly guilty thrill as if something this much fun really couldn't be legal. One day cars like this might well be legislated out of existence. In the meantime, enjoy this one while you can.