Audi RS4 vs Mercedes C63 AMG: 2012 twin test

Ever since the wild RS2 was launched two decades ago, fast estates have played a big part in Audi’s success. So it’s no surprise that the new RS4 is sold exclusively in Avant guise.

This latest in a long line of fast quattro wagons is powered by the same 444bhp 4.2-litre V8 engine as the RS5 coupe and R8 supercar. And there’s no missing the RS4 Avant, with its subtle yet aggressive styling and trademark detailing.

But the new Audi faces a stern rival, in the shape of the Mercedes C63 AMG Estate. This car’s mighty 6.2-litre V8 produces 451bhp and a thumping 600Nm of torque.

Strictly speaking, a top-spec diesel A4 Avant or C-Class Estate will have all the performance you could need, but these cars aren’t about being sensible – they’re guilty pleasures that offer mind-boggling power, plus luxury, practicality and huge desirability. There’s something uniquely appealing about these super estates, and this is sure to be a closely fought battle for supremacy.

First place: Audi RS4 Avant

Audi is famous for its performance estates and the new RS4 is one of the best yet. Surefooted handling and a sumptuous cabin make it a pleasure to live with, while accessing the car’s huge performance is easy thanks to the thundering V8 engine and slick gearbox. Options are expensive, but this is offset by the RS4’s lower price tag and healthier residuals.

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The first Audi to wear the RS badge was an estate. The RS2 Avant was co-developed with Porsche, and was an instant hit, proving that fast cars could be practical.

Jump forward nearly 20 years and the subtle yet racy styling that helped the RS2 gain cult status is still a big part of Audi’s fast estates. And the new RS4 is one of the best yet.

It’s more different to the regular A4 than the C63 AMG is to the standard C-Class, and more muscular, too. There’s chrome detailing and a latticework grille matched to a bulging body.

At the rear, twin oval exhausts hint at the potential of the 4.2-litre normally aspirated V8 – and this engine is the star of the show.

It doesn’t have the torque of the C63, but it’s gutsy and high-revving, with a relentless wave of power building through the rev range all the way to the 8,500rpm red line.

Peak power is at 8,250rpm – the Mercedes peaks at 6,800rpm – but even though it has 170Nm less torque than the C63, at 430Nm, the Audi is fearsomely fast and very flexible.

Pile on the revs, and you can savour the incredible sound, but in truth there’s so much performance on tap, you’ll rarely have space on the road to trouble the V8’s upper reaches. It’s best to save the full-rev experience for the lower gears if you value your licence.

With a test track at your disposal, you can enjoy the RS4’s explosive performance to the full. The combination of launch control and quattro all-wheel-drive traction gives neck-snapping acceleration off the line, but if you study our performance figures, it’s clear how closely Audi benchmarked the RS4 to the C63.

Both cars weigh 1,795kg and cover 0-60mph in 4.4 seconds. Only in our in-gear test was there any real difference – and even then the Audi was ahead by a mere nine-tenths when accelerating from 50-70mph in sixth, posting a time of seven seconds flat. But neither model feels anything other than scorchingly fast.

The RS4’s dual-clutch transmission is a joy, with every change fast and effortlessly smooth. As you shift up through it, there’s a lovely warble from the exhaust, while every downchange is accompanied by a throaty bark, as the automated throttle blip helps the next ratio slot crisply home.

Clever quattro and sport differential technology allows the RS4 to divide power front to rear and distribute it across the axles in search of grip. So the new car is predictably surefooted and never feels anything other than planted on the road. It doesn’t respond quite as quickly as the edgier C63, but with taut body control, massive reserves of grip and strong brakes, it’s effortlessly capable.

The electric steering feels a little artificial, although the standard Drive Select system lets you fine-tune the weighting, along with the throttle response and speed of the gearshifts – although the sportier settings don’t improve feel. And while you can take the tech tally even further, with optional carbon brakes, adaptive dampers and dynamic steering, the complexity of the Audi is already a bit overwhelming as it is. Still, there’s nothing wrong with the RS4’s cabin, with its first-class materials and subtle RS detailing. There’s a lovely flat-bottomed steering wheel which – along with the driver’s seat – is widely adjustable, and you get a more comfortable driving position and a greater sense of space up front than in the Mercedes.

The Audi’s roomier and fractionally more upmarket interior is every bit as desirable as the driving experience, and it has the edge on practicality, too: with the rear seats in place, the boot offers 10 litres more space, at 490 litres.

But while our RS4 was slightly better to drive, it’s worth bearing in mind that it had the optional sports exhaust, Dynamic Steering and adaptive dampers – to make the ride less hard-edged – which inflate the price. Yet even with these desirable options, the RS4 undercuts the C63, so it’s going to be a close finish..

Second place: Mercedes C63 AMG Estate

The margin of defeat for the C63 is tiny. Some people will find the rear-driven Mercedes more fun, but it isn’t as unflappable as the Audi in slippery conditions and the cabin is a bit cramped. Practicality isn’t in doubt, though, as the boot is huge, and the C-Class is just as fast as the RS4, yet it’s showing its age a little.

The Mercedes C63 AMG is arguably the world’s most famous fast estate, having been seen by millions in its starring role as the Formula One medical car. And it’s clearly no ordinary C-Class Estate, with its bulging arches, low ride height, quad exhausts and AMG detailing.

As with all great AMG models, the C63’s real personality comes from its hand-built engine. The Audi has a high-revving race car feel, with its 4.2-litre V8, but the Mercedes’ 6.2-litre has 600Nm of torque and provides just as much character and performance.

Turn the key and it burbles into life, while a thunderous bellow from the exhausts is just a blip of the throttle away. On the move there’s punchy performance in every gear, and while the C63 is rear-wheel drive, it matched the 4WD Audi from 0-60mph, with a time of 4.4 seconds.

The AMG Speedshift MCT seven-speed double-clutch box has Comfort, Sport, Sport Plus and Manual modes. Shifts are smooth in Manual, while the sportier settings allow the engine to rev higher before changing gear.

For the most involving driving experience, it’s best to change gears yourself, although the steering wheel paddles don’t react as crisply as those in the RS4. Away from the gearbox preferences, the Mercedes is refreshingly free of complex adjustment. The steering, throttle response and damper settings are fixed, so while you can get lost in the Audi’s menus trying to find the perfect set-up, in the C-Class you just twist the key in the ignition and go.

And it feels lighter on its feet and more alive than its rival, while the freedom of the test track lets you indulge the rear-driven chassis with beautifully balanced tail slides. But the RS4 has better body control and changes direction with less fuss.

The C63’s steering is naturally weighted and accurate, while strong brakes mean it stops as well as it goes. With standard 18-inch wheels, the ride is firm, but no worse than the Audi’s. The cramped cabin hampers comfort, though: the heavily bolstered driver’s seat obstructs your elbows and doesn’t adjust low enough.

And despite its AMG detailing and robust build, the dash design is looking dated. In the back, passenger space is okay, and with the rear bench folded, the C63 provides 70 litres more carrying capacity than its rival, at 1,500 litres.

The muscular yet family friendly Mercedes is drama and excitement one minute, and relaxed cruiser the next, but it costs more than the Audi and won’t retain its price as well. Will this hold it back?

Verdict

These cars successfully combine sensational performance with day-to-day estate practicality. Picking a winner isn’t easy, as they are so closely matched in nearly every measurable area.

Both are hugely desirable, powered by dramatic V8 engines, great to drive and beautifully built. But the four-wheel-drive RS4 is marked out by its near-unbreakable traction, taut body control and massive reserves of grip. In contrast, in anything other than bone dry conditions, the rear-wheel-drive Mercedes doesn’t inspire anywhere near as much confidence.

The C63 has more natural steering feel and feedback, while the thunderous V8 soundtrack is a delight. On the right road it’s hugely engaging, but the Audi’s engine sounds even better and the S tronic box is crisper and more responsive on downshifts.

The RS4 also looks a fraction more distinctive, has a roomier and more modern cabin, plus it’s cheaper to buy and should hold on to its price better – although neither of these cars will be bought by drivers concerned about their motoring costs.

Understated yet aggressive, fast yet practical, focused yet comfortable, the new RS4 will be all the performance car many people could ever want. So by the very tightest of margins, the hard-hitting Audi takes victory in this test.

Facts and figures