Audi's most coveted RS model returns as a high-revving V8-engined Avant, which has the numbers to ensure it's got the measure of its AMG and BMW M rivals. You have to dig deep to reveal the insanity though, and that compromises it as a genuinely useable fast road car.
In the Metal:
The A4 Avant is already a handsome car and the RS additions only enhance that further. Blistered wheelarches filled by 19-inch (or optional 20-inch) alloys and a 20mm drop in ride height add gravitas, while the two large oval tailpipes at the rear look as good as they sound. Brushed metal effect trim on the lower portions of the front bumper and larger front grille and air intakes give the RS 4 a more assertive nose too. For full q-car effect the RS 4 arguably looks best when these - and the wing mirror caps - are body coloured.
Inside it's as you'd expect, with S sports seats in leather/Alcantara, RS badging and lots of equipment. No third pedal here though, as the RS 4 is only offered with Audi's seven-speed S tronic automatic transmission. It will be sold as an Avant (estate) model only, too.
It would be futile to say that the RS 4 is anything but a ridiculously fast car, the 4.7-second 0-100km/h time underlining that. Add a top speed of 250km/h (optionally 280km/h) and it's unquestionably the fastest car in the A4 range and right on the numbers against its M3 and C 63 AMG rivals. However, what's immediately obvious on the road is the need to absolutely monster the RS 4's V8 engine for it to deliver the sort of pace those numbers promise. Blame the late arrival of its 430Nm of torque, as the rev counter's needle needs 4,000rpm on it before the V8 dishes out maximum twist. Factor in its peak power output of 450hp arriving just before the redline at 8,250rpm and the RS 4 is a car that needs wringing out to deliver.
That means you need to be on top of your game with the transmission. With seven speeds to choose from you'll be stabbing for downshifts entering a bend if the RS 4 is to deliver real punch on the exit. Corners taken in third in the Audi S4 require second in the RS 4, so it's unlikely the gear indicator will ever display anything above third or fourth on a typical Irish country road if you're intent on keeping that V8 on song.
It's quick, but needy, and the rewards are scant at all but the most obnoxious speeds. Admittedly, the 4.2-litre V8 sounds epic when it is in its sweet spot, but it's also frustratingly tardy when out of it. That makes for a disjointed driving experience, that lacks the sort of low-rev brutality of its C 63 AMG rival, or even the effortless real-world surge of an A4 with a big-banging turbodiesel under the bonnet. On the plus side, there is massive grip, incredible traction and a chassis that feels more rear-biased than any quattro Audi ought to (thank the standard fitment of Audi's Sport Differential) - so there are rewards to be had. However, the limits are so high and the speeds so great you'll be in trouble if you're caught exploring them on the road.
Fiddling with the Drive Select system allows selection for Dynamic, Automatic or Comfort preferences on everything from the suspension, to the steering (if the optional dynamic steering and Dynamic Ride Control have been selected). Everything on Dynamic seems to work well, with the suspension on Automatic to smooth out the ride when the road is less than perfectly surfaced. The steering offers heft, but feel is lacking at the perforated leather covered wheel rim.
What you get for your Money:
At the top of the A4 range the equipment list is unsurprisingly comprehensive. Along with the gorgeous leather/Alcantara seats and 19-inch alloys, a flat-bottomed leather steering wheel is standard, as is Audi drive select, park system plus, Bluetooth, tracker preparation, electrically folding door mirrors and lots more besides. The RS 4 Avant is incredibly good value at just over €100,000 - all things being relative of course...
Officially the RS 4's V8 delivers 26.4mpg (10.7 litres/100km) on the combined economy cycle, but you'll get nowhere near that on the road. If you're off to Germany regularly the 250km/h electronic limiter can be raised to 280km/h. Ceramic brakes are also available for the front axle, saving 4.5kg of un-sprung weight over the standard brakes.
Audi's RS concept of a high-revving engine is definitely fulfilled here, but it doesn't translate that convincingly to the road. It's unquestionably quick when pressed hard, but largely devoid of any thrill at anything but the most ridiculous speeds, which results in a frustratingly disjointed driving experience.