Mercedes-Benz C63 vs Audi RS4

What's the difference?

The Mercedes-AMG C 63 S Aero Edition is an absolute beast of a car, but it comes at a pretty hefty price. Yes you get a lot of performance, and the fact there are only 63 examples being made for Australia and New Zealand could be enough to get you to sign on the line. For me, though, if I was after a C 63, it’d have to be a wagon. It doesn’t need an Aero pack to look better.

What a way to send off this generation of Audi RS4 and RS5. The extra focus courtesy of those trick coil overs and drama from the exhaust plus the sharper gear changes deliver the best Audi has done with these RS products. 

There are some compromises, with the suspension favouring outright control over low-speed comfort. It’s also true that the current BMW’s M3 and M4 are more impressive, but when the products are nearly seven years fresher than Audi’s, what do you expect? 

Plus, those looking for a more restrained and polite fast executive sedan (or wagon) will gel with the Audi’s sophistication. There aren’t many of these Competition Plus RS4 and RS5s coming to Australia and they are impressive visually and from behind the wheel. It’s a fitting way to send off the current generations.

Note: CarsGuide attended this event as a guest of the manufacturer, with accommodation and meals provided.

I’ve never been the biggest fan of the current C-Class Coupe’s styling. To me, it has always looked a little droopy, a little melted at the back. 

I have to say, the Aero Edition has changed my opinion somewhat, as the new graphic elements help lift it up a bit, visually raising its rear up like a stretching cat, tail in the air. I’m still not 100 per cent on it, but to my eye it’s better.

The carbon-fibre trim elements that have been added to the exterior certainly add some menace to the look, too, and I simply can’t help but constantly notice out of the corner of my eye the AMG pressing in the staggered, dished rims. At a glimpse, from a distance,  it looks like rim damage, but thankfully it’s not!

The staggered set-up does really add some width and mongrel to the look, as if it needed more, with its open maw lower bumper air dam, and the signature 'Panamericana' grille treatment which looks like an evil character out of a movie. If you know the one I’m talking about, let me know in the comments.

As much as the look matters when it’s parked in your driveway, it’s the cabin that arguably matters more, right? That’s where you spend your time, after all. Check out the interior images to see if you think it lives up to the exterior look.

The RS4 Avant’s 'Progressive Red' metallic helps the black milled 20-inch alloy wheels pop. Its stance is hugely purposeful with wheels tucked right up in the blistered arches courtesy of the lowered ride height — it's how the Avant would have looked in a design sketch.

The visual bulk of the long-roofed RS4 gives it the sort of proportions motoring journalists love to wax lyrical about, even if plenty of buyers still prefer coupes or lifted SUVs. 

The RS5's more flowing, elegant lines match well with the Navarra Blue paint work, silver-accented wheels and conventional leather-appointed seats within. 

Both cars have effectively identical front cabins reflecting Audi’s classy and sleek design language. The integration of technology is pretty good and the RS4’s additional red styling pack really makes it feel sporty within.

No two-door coupe is going to offer you the space and comfort of a sedan or wagon, that’s just a fact. But that only matters if you plan to actually use the rear seats. If you don’t, then the Coupe version of the C 63 S might be perfect for you.

Even so, I managed to (only just) squeeze myself between the seat and the door opening to slide into the rear row. This won’t be easily achieved by all attempters, especially on the driver’s side.

Let’s just say I probably looked like I was doing something very weird to the driver’s seat as I spider-manned my way in. 

The rear space is tight for someone my height (182cm/6’0”) behind their own driving position, with knees hard-up against the seat in front and not much headroom (my noggin’ was brushing the ceiling) or toe space (size 12s don’t fit so well) to speak of.

It’s certainly a selfish car. Or maybe it’d be fine for smaller kids. There are two spaces in the back, both with ISOFIX child seat anchors and top-tether points.

But there is storage in the back - cupholders and storage caddies either side of the seats, though the storage situation improves in the front zone, with bottle holders in the doors, cupholders between the seats, loose item storage under the media screen and a covered centre armrest bin, too.

The front cabin is a special looking place, with carbon-fibre abounding across the dash and nice trim on the doors. The AMG steering wheel is a sight to behold - it’s a flat-bottomed unit with carbon-fibre and Dinamica (that’s Benz talk for microsuede) trim: perfect for sapping sweat as you manhandle the C63 through the bends.

The seats are AMG Performance sports units up front, and the trim used is reserved for this model specifically: Nappa leather with yellow stripes. There are yellow details elsewhere, including on the rear seats, centre console and dash, and it certainly adds some visual excitement.

Media is controlled by a 10.25-inch display and Mercedes-Benz’s touchpad control system, but there is no touchscreen - rendering the Apple CarPlay and Android Auto smartphone mirroring technology somewhat tedious.

I’ve always had a gripe with screens that don’t allow touch but feature the tech that’s designed to transfer your phone’s screen to the media unit, and I can tell you the longer you spend twiddling the dial to get where you want to go, the more annoying it becomes.

The Burmester sound system has 13 speakers and is rather good, but I prefer the sound from the standard fit variable sports exhaust. So maybe that quibble with CarPlay isn’t that big a deal.

And if you just want to charge your phone, and there’s a second USB port up front, as well. Note: in non-Aero Edition C 63 models without the carbon-fibre interior pack, you also get Qi wireless phone charging, but it’s deleted from this variant and any model with the carbon pack.

The driver has a 12.3-inch digital info display to show where you are and what the car is up to, and there’s a head-up display as well. Yep, there’s standard sat nav with live traffic updates (and even live fuel price updates) - it’s just a shame the maps still look early 2000s-spec in 2D layout.

Cargo space is okay. The claimed cargo capacity or boot volume is 355 litres (VDA) with the rear seats in place. That’s small for a coupe of this size, and the shape of the boot (with a hump behind the rear seat) isn’t great as things do move around quite a bit.

But, thankfully, Mercedes has included its clever foldable storage box system under the boot floor - it goes where you might usually expect a spare wheel, but there isn’t one in this car. Instead you get Mercedes’ 'Tirefit' repair kit with an electric pump.

The RS4's cabin is excellent, with a good mix of physical buttons and responsive touchscreens for control. There’s enough storage space for this kind of vehicle, with good door bins and well-sized cupholders in the centre as well as USB-C and -A charge points. 

Audi’s multimedia system is friendly though the large touch targets and dark background aren’t as crisp as those fitted to the latest rivals. The screen isn't as big, either, measuring 10.1 inches for the multimedia item. The RS4 supports wireless Apple CarPlay and Android Auto.

That said, Audi’s 12.3-inch digital driver’s display with bright and poppy mapping software and generous customisation remains right at the head of the pack. 

There is a panel of switches below the touchscreen for climate control, physical selection of the five-or-so drive modes and a collection of helpful buttons on the perfectly-shaped and sized leather-appointed steering wheel.

It lacks F1 or DTM wow-factor compared to the C63 and M3 with their easy-access driver mode buttons and toggles on the steering wheel but the RS4's restrained looks will resonate with those that prefer a bit more elegance inside. 

Neither the RS4 nor RS5's back seats are designed for those over about 175cm. The RS4’s roof is a little higher so it is good enough for most adults but the RS5’s sloping profile compromises things. It has two individual buckets compared to the RS4’s three-wide bench. 

Rear seat passengers get air vents, an individual climate zone, bottle holders in the doors, USB charge points and ISOFIX attachments for the outboard seats, with matching top tethers in the seat backs.

The Audi RS4’s boot is a generous 505L with under floor storage and a netted area on the driver’s side. Folding the 40/20/40 split-fold bench increases space to 1495L. That said, the RS5’s 465L is still very good, though it is not quite as practical in the real world. 

Being fitted with roof rails makes for sleek integration of roof racks for the RS4 to slip roof pods, bike racks or whatever else you might choose to take on a trip away.

You'd expect the RS5 to be more popular given how uncool wagons are these days but Audi's whole thing is wagons — or Avants, for the initiated — so it makes sense that the RS4 Avant outsells the RS5 Sportback about two-to-one.

For the RS4 Avant’s basic asking price of $165,015, before on-road costs, you get luxury features such as LED headlights, an RS design package, Nappa leather upholstery, power-adjust seats, a Bang & Olufsen 19-speaker sound system and metallic paint on top of the significant changes to the RS4’s chassis and zingy 331kW V6. 

The RS5 is a little dearer, reflecting the addition of Matrix LED headlights that aren’t available on the wagon.

But we have the 'Competition Plus Pack', which is a $13,990 indulgence that swaps adaptive dampers for Audi’s 'RS Sport Suspension' coil over package with manual rebound and compression adjustment and height adjustment.

The cars sit 10mm lower than a normal RS4 but you can go to a dealer to move the ride height up or down from there. 

That’s not it, though. You also get a louder exhaust system with matte black pipes, fixed-ratio steering system, a retuned eight-speed automatic with more aggressive shifts, different rear differential programming, black exterior badging, 2.0kg lighter 20-inch Audi Sport wheels (in silver or black), special LED entrance lights and your speed limiter raised to 290km/h.

The 'Navarra Blue' RS5 pictured is a ‘basic’ Competition Plus. You can go further, as done with the RS4 Avant with its manual-adjust bucket seats ($1300), 'Interior Design Pack' in red ($3400), matte carbon exterior pack ($6300) and carbon trim, bringing its total cost to $191,405, before on-road costs. 

That makes the RS4 and RS5 the most affordable in their competitor set, below a BMW M3 Competition xDrive Touring ($183,500) and Mercedes-AMG C63 S E Performance hybrid, which is $187,900, before on-road costs.

Open the shapely bonnet of the C 63 S and you’ll find a hand-assembled horsepower-monster engine with a printed name plaque to prove it.

The 4.0-litre twin-turbo V8 produces 375kW of power at 6250rpm, and 700Nm of torque from 2000-4500rpm. It runs a standard-fit nine-speed 'Speedshift MCT' (multi-clutch transmission) automatic, and it’s rear-wheel drive. And yes, that means it likes to boogie.

The claimed 0-100km/h time is just 3.9 seconds, and top speed is apparently pegged at 250km/h. Yeesh.

The name on the “Handcrafted by” plaque on this particular engine? Hat tip to you, Julian Rembold. This is quite a piece of work. 

Audi’s 2.9-litre twin-turbo petrol V6 has seen plenty of use across performance products from Audi and Porsche, including the Macan S and Audi S6. 

In the RS4 and RS5 Competition Plus, it develops the same 331kW (at 5700-6700rpm) and 600Nm (at 1900-5000rpm) as the regular car. This makes it an extremely flexible engine that delivers predictable punch anywhere in the power band.

That said, it lacks the explosive character of BMW’s twin-turbo inline six — the figures are only 15kW and 50Nm higher on paper yet the M3’s response is that much more ferocious. 

Audi’s RS division has tried to capture a bit more emotion, retuning the eight-speed torque converter automatic transmission for crisper shifts. This also benefits the RS4’s 0-100km/h sprint time, which falls two tenths to 3.9 seconds in Competition Plus guise. 

The V6 breathes a little easier, too, with a different exhaust. Audi says the extra sound is down to 8.0kg less sound deadening in the car.

There’s more resonance at idle that does feel tiring sitting in traffic idling but the trade-off is a brawny mid-range baritone that develops into a shrill bark approaching the redline.

High numbers are what AMGs are about. Sadly that’s the case not only for performance outputs but also fuel consumption.

The official combined cycle fuel use claim for the C 63 S Coupe is 10.3 litres per 100 kilometres, and you need to fill it with 98RON premium unleaded fuel, too.

On test? Well, across a mix of different driving - urban, highway, back road and spirited stints - I saw an 'at the pump' return of 12.2L/100km, while the digital readout stated 12.0L/100km.

Given the performance on offer, and how much I took advantage of it during my week with the car, that’s not bad…

Fuel tank capacity is 66 litres. So go easy if you know there won’t be a fuel stop for a while.

The Audi RS4 wagon is rated to use 9.5L/100km in ADR combined cycle (urban/extra-urban) consumption testing while the slipperier RS5 returns 9.4L/100km in the same test. 

We weren’t able to run accurate or particularly relevant fuel figures on the event but the trip computers showed around 12L/100km in both RS4 and RS5. 

While these numbers are high compared to your average passenger car, the Audi is more efficient than BMW's rivals, and gets remarkably close to the hybrid C63 in the real world.

The fuel tank is quite small for this kind of vehicle at 58 litres. That limits the RS4’s theoretical driving range to 611km. 

Unsurprisingly, the Audi RS4 and RS5 require 98 RON premium unleaded petrol. 

Just one word sprang to my mind when it comes to accurately describing the performance on offer from this car. The word is ‘brutal’.

Smash the accelerator and the power and torque on offer is enough to make your eyes feel like they’re not doing the right thing anymore. You get pushed back in your seat with a surge, and your ears are also rewarded with one of the best soundtracks in the automotive world. 

The engine builds pace with enormous intent, and the sound that comes from under the bonnet and out the back through the exhausts is addictive.

Yes, there is an active exhaust button which you have to press to make sure that you hear all that noise if you’re running around in 'Comfort' mode, and during my time with the car it was active the whole time.

I had some questions from neighbours over the week that I had this car about whether it was actually nice to live with on a day-to-day basis. And the answer is yes, if you put it in comfort mode it’s surprisingly amenable. 

The ride is really well sorted at pace despite having a bit of that trademark low-speed wobble that seems to afflict Mercedes products from A-Class through to the GLE SUV. But it wasn’t bad enough to really bother me, as most of my time was on highways and backroads.

The steering is direct and accurate. The only thing you need to be aware of is that you will lose traction at the rear axle when you put your foot down hard. And for the enthusiast that’s exactly what you want. 

I know I want to feel the thing squirm under throttle. It’s a rear-drive V8 coupe, after all. You want to feel like you’re a vein in its bicep muscle; you know, the one you see in a weightlifter’s arms – the one that wiggles around a lot. You want to have that. Right?

On the performance front it is exceptional. Twist the little dial on the wheel to 'Sport' or 'Sport+' (I didn’t sample 'Race' mode as I wasn’t at a racetrack), and everything feels like it’s had a protein shake.

Even so, in that mode it steers brilliantly, there's a nice feel through the wheel, and the ride, while stiff, controls the body brilliantly when you change directions. 

The transmission is very good, too. In Comfort mode it can take just a second or two at first to become accustomed to the idea that you want to drive aggressively.

But in Sport mode, or when you select the manual transmission mode using the trigger button on the steering wheel, you will certainly get the most out of the engine. That’s what I did when I was driving it in a ‘spirited’ manner.

If you are just after that high-end Coupe cruiser experience, it’s a relatively quiet car (provided the surface below isn’t the coarsest of coarse-chip bitumen), with enough luxuriousness to make it feel premium as well as sporty. That’s an important thing to consider, especially at this price point.

The time allocated to driving the RS4 Avant Competition Plus was fairly limited and we were sadly unable to sample how the highly adjustable coil over suspension performed where it makes most sense — on the racetrack. 

Still, winding country roads between Sydney and the Southern Highlands served up some challenges, demonstrating how the Competition Plus pack changes the character of the RS4 and RS5. 

The only real negative is comfort, specifically over those horrible plastic speed bumps that litter shopping centre car parks. With adaptive dampers, carmakers can set programs for these kinds of obstacles to soften and stiffen the clever shocks at just the right time. Not so the Competition Plus pack cars, which ride these bumps harshly.

That about does it, though, and everything thing else is a net benefit. The steering system addresses some criticism of the earlier RS4s. Further than a retune, the Competition Plus gets a new rack, that is non-progressive with a fixed ratio of 15:1 (instead of 13.3:1) and 2.4 turns lock-to-lock. The reactions to each input feel a hint more faithful. 

When above 40km/h the coil overs come into their own. Even though the RS4 rides firmly it doesn’t constantly jiggle over small bumps. Over sharp-edged hits, the suspension rounds the hits off so, while you feel them, there’s a sense of control and sophistication. 

Having speed limits to contend with means it is essentially impossible to find the limits of grip of the 275/30R20 Continental SportContact 6 tyres on the road and there isn’t much body roll, either.

The RS4 is still rewarding, though, getting up on its toes just enough through a series of bends to feel engaging. It gives an impression of being quite light and at 1820kg it is now considered featherweight next to rivals.

The RS4's Quattro all-wheel drive system favours the rear wheels when driving normally (60 per cent rear) and can send up to 85 per cent of the drive to the back axle. 

The tweaked electronically-controlled rear limited-slip differential amplifies the throttle steer-ability of the RS4, giving you the confidence to squeeze the gas on exit. 

It helps that the Competition Plus bucket seats are a little thinner and set closer to the floor giving you more feedback. This is the key differentiator between the RS4 and RS5 we drove — the buckets make the car feel alive. 

Strong brakes are made up of 375mm front rotors clamped by six-piston calipers. Optional carbon ceramic brakes with larger 400mm front rotors help save 6.5kg and, if you plan to use the RS4 on track, are a smart buy along with a set of Pirelli P Zero Corsa semi slick tyres ($850). 

Really, though, neither the RS4 nor RS5 are the perfect car for the track. They are plenty capable and fast on the road with just enough fun, reward and character thrown in to keep you coming back for more.

The Audi A4 range was rated a maximum five stars in ANCAP safety testing in 2021, with the rating now considered expired. The stamp also only applied to four-cylinder models — so not the RS4 we drove. 

It has lots of safety equipment, including eight airbags (dual frontal, side chest, front and rear side head curtains), autonomous emergency braking (AEB) functional up to 250km/h with pedestrian detection, front and rear cross-traffic alert, lane-keep assist, blind-spot monitoring, safe exist warning and tyre pressure monitoring.

Adaptive cruise control with lane-trace assist makes it an easy car to use on the motorway. The systems are well integrated and easy to switch on and off as you like. 

Mercedes-Benz is among the minority of luxury brands now offering a five-year/unlimited kilometre warranty plan - most still have three-year cover. So that’s a tick.

And the service intervals are pegged at 12 months/20,000km. Another tick.

Plus you can either pre-pay your service plan in three-year ($3800), four-year ($6000) or five-year ($6550) plans - roll it into the finance package, and it won’t hurt quite as much.

According to Mercedes, the three-year coverage option makes for a $900 discount over pay-as-you-go servicing.

Roadside assistance covers the five-year new car warranty period, too. So Mercedes seemingly takes good care of its customers. But if you have any concerns or questions over reliability, problems, issues or complaints about the C 63, check out our AMG C 63 problems page.

Audi covers the RS4 and RS5 with a five-year/unlimited kilometre warranty which is now the expected norm across the premium part of the market. 

A five-year service plan can be pre-purchased, costing $3630 for both models with maintenance due annually or every 15,000km. 

After the five-year warranty period, owners can choose to extend the service packaging and warranty for two extra years at a cost of $4260. This can be done twice, extending the warranty up to nine years.