Audi RS7 vs Mercedes-Benz SL63

What's the difference?

The new-generation RS 7 Sportback heralds the further evolution of this large majestic beast, with more features, a beautifully finished cabin and with more grunt with the looks to match. You’d be hard-pressed to find a better combination of power, dynamics and comfort in the Audi range – apart from in the RS 6 Avant of course.

The new Mercedes-AMG SL63 4Matic+ is guaranteed to turn heads for decades to come. But there’s enormous design and engineering substance underpinning this car’s undoubted good looks. Stunning performance, superb dynamics and top-shelf safety make this a powerhouse GT to be reckoned with.

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

The big news is the RS 7 Sportback now comes with five seats. The previous generation car had just two seats in the second row. I'll talk more on practicality below but for now let's examine the new styling.

This RS 7 Sportback has new broad, black mesh grille, flanked by gigantic side air intakes, narrow headlights, and a thin upper air inlet which is a hat tip to early racing Audis.

While that new angrier, more angular and menacing face is a showstopper, everything about the new RS 7 Sportback seems to be accentuated further.

Look at the wheels. The previous generation came with 21-inch rims, now the new normal for the RS 7 are 22-inches – they're huge. Those wheel guards also flare out 20mm more than a regular A7's and the rear haunches have bulked up massively.

Come to the back of the car and the diffuser and bumper have also been beefed up. Nobody sitting behind you in traffic is going to think this is just a regular A7.

Don't expect the RS 7 Sportback's insides to be just as hardcore as its exterior. The cabin is almost identical to a regular A7's. It's a stunning cockpit dominated by a dash which protrudes back towards the passengers and houses the media screen. Anther display for climate is set into the big centre console which divides the driver and co-pilot into almost cocooned cells.

The cabin isn't without its RS touches though – there's the sports seats with honeycomb stitching, fully digital instrument cluster with RS specific meters, the RS steering wheel, the Nappa leather on the dashboard and the doors, the aluminium inlays. The level of fit and finish is up there with the best that I've seen on any production car.

The RS 7 Avant is 5009mm long, 1424mm tall and 1950mm across for a wide planted stance.

Rather than a strict two-seater, this time around the SL adds the flexibility of ‘+2’ rear seating while the previous 'Vario’ folding hardtop has been binned, the new car returning to a traditional, electrically-folding and weight-saving (-21kg) soft top. 

Mercedes-Benz design chief Gorden Wagener started the new model’s development from a ‘clean sheet’ and Mercedes-AMG says “not a single component comes from the predecessor SL, or any other model such as the AMG GT Roadsters”. 

Always a subjective call, but I think this car’s proportions are just about perfect. The lengthy bonnet with its twin longitudinal ‘Power Domes’, raked windscreen and fat haunches create a wide stance and presence that’s almost impossible to ignore.

Aggression, as with the sinister headlights and 21-inch rims, is subtly combined with soft curves along the flanks and around the rear. Note the seamless door handles.

And it’s not all about aesthetics. Active aero has been integrated into the front apron and retractable rear spoiler. Plus the ‘Z-fold’ roof design does away with the need for a separate cover.

The interior is sub-zero cool with slick screens, an 11.9-inch display covering multimedia and a 12.3-inch unit for instrumentation ahead of the driver, being particular highlights.

Turbine-style air-vents at the leading edge of the split-level dash and alloy trim elements are a tip-of-the-hat to SLs past and the deft mix of large flat surfaces with complex curves oozes design confidence.

The previous RS 7 Sportback was a four-seater, now it has five seats. That's right, a middle seat has been added to the second row, but, as you'd expect, it's not the best place be in the RS 7 Sportback, straddling the large driveshaft and ducking under the low roof-line.

That fastback profile does mean headroom in the second row is nowhere near as good as the RS 6 Avant's, but legroom is the same and, at 191cm tall, I can just fit behind my driving position with about 10mm to spare.

Up front it's not as spacious as you might think. That stepped dash protrudes into the passenger's space, the door pockets are thin and the centre console storage under the armrest is small.

Sportbacks are more practical sedans thanks the large opening offered by the hatch. The boot's 535-litre cargo capacity is great and only about 30 litres less than what you have in the RS 6 Avant.

For phones there's a wireless charger and two USB ports in the centre console storage box, while back seat passengers have two USB ports and a 12V outlets. There's also directional air vents and dual-zone climate control in the rear, too.

In the context of a high-performance GT, practicality is pretty impressive.

At just over 4.7m long the SL is a sizeable machine and much of its lengthy (2700mm) wheelbase is devoted to making the driver and front passenger comfortable.

There’s plenty of space for that pairing and just enough storage to cope with the ‘things’ they’ll typically bring with them.

Door pockets offer enough room for a few odds and ends, although you’ll struggle with even a medium-size bottle unless you’re willing to lay it down horizontally along the top of the aperture.

A handy lidded bin between the front seats doubles as a centre armrest, there are two cupholders under a sliding lid in the centre console and the glove box is a decent size. 

Power and connectivity options run to four USB-C ports, a 12-volt socket and the wireless device charging pad.

Then there are the rear ‘+2’ seats, and Mercedes makes no bones about the fact they’re intended for occasional use only, even suggesting a 1.5m occupant height limit.

And there’s no doubt they offer a handy emergency seat or a fun kids’ zone. Just ask a Porsche 911 Carrera owner how much this kind of seating arrangement increases a sports car’s flexibility.

At 183cm I gave the back seat a crack, which meant sliding the front (passenger) seat way forward with the backrest close to upright. But I squeezed in, and there was just enough legroom for a person in front at the same time. 

With the roof in place there’s the added pleasure of cranking your head over to around 45 degrees. But it’s do-able! 

No storage, adjustable ventilation, or power back there. But that’s fair enough, especially given there are USBs available in the front centre storage box.

Boot volume is 240 litres with the roof up and 213 litres with it folded, which is enough for some light luggage, and not too shabby when you think a Toyota Corolla hatch offers up just 217 litres (with all seats up).

There’s a 12V socket in there, but don’t bother looking for a spare, in the event of a flat your only option is a repair/inflator kit.

Priced at $373,370, before on-road costs, the new SL63 4Matic+ will be battling top-shelf performance soft tops including (in ascending dollar order) BMW’s M850i xDrive Convertible ($307,100), the Porsche 911 Carrera GTS Cabriolet ($386,900) and even exotics like the Lamborghini Huracan RWD Evo Spyder ($422,606). 

Value for money is a relative concept in this part of the market, although equipment highlights include a head-up display (with augmented reality nav), 11-speaker, 650-watt Burmester surround sound audio, ambient lighting (choice of 64 colours), hectares of Nappa leather trim, dual-zone climate control, an 11.9-inch central multimedia screen (running Merc’s latest ‘MBUX’ software), 12.3-inch configurable digital instrument display and 21-inch forged alloy rims.

There’s also the ‘Digital Light System’ built around three high-power LEDs in each headlight, refracted and directed through 1.3 million ‘micro-mirrors’ to create a combined resolution of 2.6 million pixels.

The ‘Neck Scarf’ function is added to the top of the front seats to keep your neck and the back of your head warm as the temperature drops, the heated, ventilated and massaging front seats feature eight-way electric adjustment and three memories, there’s a heated steering wheel, Android Auto and Apple CarPlay connectivity, wireless device charging and more.

Worth noting the big 21-inch rims in a ‘10-twin-spoke’ design are standard issue with an alternate ‘multi-spoke’ pattern available as a no-cost option. 

But if all that’s not enough you can opt for ‘AMG Performance seats’ ($2490) which grip you even more securely but delete the massage function.

Or there’s the ‘AMG Night Package’ ($6990) which adds wheels in matt black (with “high-sheen finish rim flange”), darkened head- and tail-lights, an aero package, black badging, black radiator fins and interior trim elements in black chrome.

Then you can go the whole hog with the ‘AMG Carbon Fibre Package’ ($11,990) which brings the wheels in matt black, exterior carbon elements, carbon mirrors, carbon interior trim and a steering wheel in a combination carbon-fibre and Dinamica (synthetic microsuede).

The RS 7 may look like a large, well-mannered business class car, but think of it as a thug in a suit because this thing is a monster with a 441kW/800Nm twin-turbo petrol 4.0-litre V8.

That's almost 600 horsepower and the supercar acceleration that goes with it is brutal: we're talking 0-100km/h coming in 3.6 seconds. That also matches the RS 6 Avant and it's a tenth of a second faster than the Audi R8 V10 RWD supercar, (and also the previous-gen RS 7 Sportback Performance) and this is a large, four-door, five-seater.

Compared to the previous generation RS 7 Sportback Performance the power is down by 4kW, but torque is up by a whopping 100Nm. Give me torque over power any day.

Shifting gears is an eight-speed automatic transmission, sending the drive to all four wheels.

This new ‘4Matic’ all-wheel-drive SL63 features AMG’s (M177) 4.0-litre twin-turbo V8, superseding the previous rear-wheel-drive SL’s similarly configured 5.5-litre unit.

Hand built by one AMG technician from start to finish, it produces 430kW (around 580hp) from 5500-6500rpm and 800Nm across a broad plateau from 2500-5000rpm.

It’s something of a mechanical masterpiece, and the previous seven-speed auto transmission, driving the rear wheels only, has been replaced by a nine-speed dual-clutch auto (with wet multi-disc start-off clutch) sending drive to all four wheels via Merc’s ‘4Matic’ AWD system.

This is a large, all-wheel drive car with a 600 horsepower V8, but it also has a mild hybrid system in this new generation, which will switch the engine off at let the car coast down hills or at speeds under 22km/h.

Audi says this can save up to 0.8L/100km in real-life driving. That's great news, but consumption is still fairly high with Audi saying that after a combination of open and urban roads the RS 7 Sportback will have used 11.6L/100km.

Mercedes-AMG’s official fuel economy number for the SL63 on the combined (WLTP) cycle is 13.9L/100km, the 4.0-litre twin-turbo V8 emitting 319g/km of CO2 in the process.

On the roughly 300km launch program we covered urban, B-road and some freeway running, returning an (indicated) average of 17.5L/100km. And that reflects some enthusiastic driving along the way.

The fuel tank requires 70 litres of 98 RON premium unleaded to fill it which translates to a theoretical range of around 500km, dropping to 400km using our real-world number.

I've never met an RS model that hasn't been great to drive – these cars are way more than just tough body kits and big wheels. The engineering which separates the RS 7 Sportback from the A7 makes them more distant cousins than siblings.

As I mentioned before the RS 7 Sportback and RS 6 share more than the same twin-turbo V8, there are also the giant brakes in form of 420mm discs at the front with 10 piston calipers and 370mm discs at the rear.

The optional carbon ceramic brakes are the largest ever to be fitted to a production vehicle at 440mm at the front and 370mm at the rear, saving 34kg in mass over the steel brakes.

Now standard for the first time is Audi's Dynamic Package, which adds dynamic steering (a variable ratio) paired with all-wheel steering, a sport differential, and a 280km/h top speed.

Coming standard is adaptive air suspension and for $2850 you can option the Dynamic Ride Control suspension, which is a hydraulically activated adaptive damper system 

At the Australian launch, Audi supplied two RS 7 Sportbacks: one with the air suspension and the other with not only the Dynamic Ride Control system, but also the RS Dynamic Package Plus which adds the ceramic brakes and increases the top speed to 305km/h – this was the car I started off in.

I'm going to say right away that you don't need ceramic brakes for regular road use. Sure it means you can tell people that you have the biggest brakes in the world and they save you almost 35 kilos in weight, and, yes, they're resistant to fading, but they're expensive to replace and the steel ones are incredibly good.

I also feel the Dynamic Ride Control sports suspension isn't necessary in a car like the RS 7 Sportback. This is a Grand Tourer designed to eat up hundreds of miles at lightspeed in comfort.

So, while I found the first RS 7 Sportback with the big brakes and sports suspension sharper and firmer than the standard car, it didn't seem to fit with this vehicle's intent.

The regular RS 7 Sportback still accelerated with the same brutal force and roared at the scenery flashing past. It still handled through the tight corners superbly with excellent turn in, mind-boggling traction and grip, and excellent body control, but all in far more comfort.

This is the point – we covered hundreds of miles at the Australian launch of the RS 7 Sportback in a range of RS models, and sports suspension can go from great to gruelling on Aussie roads with their coarse-chip bitumen and potholes. The RS 7 Sportback, with its air suspension, not only made driving far more comfortable, but easier, too.

I recall driving the AMG SL65 around the backroads of Tassie a few years ago and that twin-turbo V12 monster famously packed 1000Nm of torque, while this car ‘only’ has 800.

But there comes a point where enough is enough… and this is enough!

With maximum torque available from 2500-5000rpm and peak power (430kW) on call from 5500-6500rpm there’s always stupendous acceleration available with a squeeze of your right foot.

Claimed 0-100km/h time is supercar fast at 3.6 seconds, while top speed is a toupe-troubling 315 km/h. And that’s electronically limited!

A typically ferocious engine noise and howling exhaust note accompany rapid progress and shifts from the nine-speed dual-clutch transmission are quick and positive, not to mention especially enjoyable using the steering wheel-mounted paddles.

There are six ‘AMG Dynamic Select’ drive programs from Comfort through to Race, the latter including a Drift Mode, which we didn’t experiment with. Nor did we dip into the ‘AMG Track Pace’ system for circuit-focused mapping and timing

However, far from drifting, the grippy Michelin Pilot Sport 4S rubber (275/35 fr - 305/30 rr) plants the car securely with the all-wheel-drive system and electronic locking rear diff playing their part.

I found the perfect set-up was in the ‘Individual’ mode with the engine, transmission and steering in racier settings and the suspension in ‘Comfort’. The adaptive damping in this configuration mixes smooth ride compliance with sharp dynamic response.

The car’s aluminium space frame chassis is part of a body structure mixing aluminium, magnesium, fibre composites and various strength steels.

Torsional rigidity is claimed to have been improved by 18 per cent and despite the lack of a roof the SL feels tight and solid.

Suspension is by alloy double wishbones front and rear with adaptive damping and active hydraulic anti-roll stabilisation standard (so, no physical anti-roll bars).

At the same time the 4Matic AWD system is able to vary torque distribution up to 100 per cent to the front or rear axle depending on where drive can be put to best use.

The speed sensitive, variable ratio, electronically controlled steering is accurate and turns in beautifully with good road feel. No doubt assisted by electric rear steering able to adjust the angle of the rear tyres by up to 2.5 degrees.

All this adds up to a hugely impressive package that, despite its 1970kg kerb weight, feels agile, athletic and able to attack corners like an overgrown hot hatch, putting its power down with unwavering authority.   

While indecently fast the SL63 can also stop rapidly with the AMG high-performance braking system standard. 

Huge composite ventilated and cross-drilled discs (390mm fr - 360mm rr) are clamped by six-piston fixed alloy calipers at the front and single-piston units at the rear. They wash off speed calmly and consistently with perfect pedal feel.

Even at highway speeds, particularly with the windows up, normal conversation is easy with the roof down. But if you need to raise (or lower) it, the operation takes 15 seconds and is possible up to 60km/h. 

Under the heading of miscellaneous observations, the turning circle is a not insubstantial 12.8m, so beware in the car park.

A front axle lift function is a welcome standard feature, raising the car’s nose 30mm with the press of a button. And lift locations are stored in GPS data, so the car will subsequently remember to lift itself at the same place, even if you don’t! 

Heating and cooling for the front seats combined with the heated steering wheel and Air Scarf neck warming makes winter top-down driving a pleasure.

The digital instrument display is not only crystal clear, it can be changed through multiple configurations, including a tunnel-like graphic for engine revs as well as specific readouts for speed, g-force, the lot.

At the same time, the central media screen’s angle can be adjusted to better cope with reflections and the windscreen wiper system Merc calls ‘Magic Vision Control’ channels fluid along the wiper arms onto the rubbers, which isn’t new, but works spectacularly well here.  

No independent ANCAP safety assessment at this stage but the SL63 is fitted with the ‘Driving Assistance Package Plus’ which includes a heap of active (crash-avoidance) tech including AEB (with pedestrian detection), active cruise control, lane keeping assist, lane change assist, traffic sign assist, ‘Active Traffic-assist’ and ‘Active Steering Assist’. 

There’s also tyre pressure monitoring and the ‘Active Parking Assist with Parktronic’ self-parking system supported by a 360-degree camera view and multiple sensors. 

If a crash is unavoidable the airbag count runs to eight, including side bags for rear occupants. There are ISOFIX anchor points for child seats or baby capsules in the two rear and front passenger seat positions. And an active bonnet is designed to reduce injuries in the case of a pedestrian impact.

The RS 7 Sportback is covered by Audi's three-year, unlimited kilometre warranty which not only falls behind in duration compared to mainstream brands but also its direct rival Mercedes-Benz which now has five-year, unlimited kilometre coverage. 

Service intervals are every 12 months or 15,000km with a three-year plan costing $2380 and a five-year plan for $3910.

The SL63 4Matic+ will be covered by Mercedes-AMG’s five-year/unlimited km warranty, with roadside and accident assistance included for the duration, both of which are expected in this category. 

Maintenance intervals are 12 months/20,000km, and a fixed-price service plan lists an average of $1583 for each of the first three visits to the workshop. Not exactly small change, but not unheard of in this part of the market.