Mercedes-Benz AMG GT vs Mercedes-Benz SL-Class

What's the difference?

This is no Lotus, but damn if it ain't a hell of a good time, and proof positive that electrification can enhance the V8 experience, rather than ruin it.

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.

It's a mean, but somehow still sleek, looking beast, this big AMG, but it's also immediately recognisable as a thing of intent.

Up front, there's the huge vertical-slat grille that looks like it drove straight out of a Stephen King novel, a massively domed bonnet, and these vacuum-like side intakes that look like they could suck in stray animals.

Then, at the back, there are twin dual-pipe exits (for four in total), and an automatic wing that pops out of the rear bodywork. And all of that's capped off with these massive 21-inch forged alloy wheels hiding golden ceramic-composite brakes.

Mean, yes, but not quite as aggressive as you might expect the most powerful AMG to date to come across, perhaps.

Inside, it's more subdued again, with the AMG presenting a pretty passenger-friendly space, with all the Benz tech you'd imagine, including the massive screens, and — thanks to its air suspension and drive modes — the ability to tailor the ride to your liking, meaning a comfortable and premium experience, despite the power under your right foot.

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.

It's not overly practical, given its size, with AMG locking in a four-seat configuration with a fixed rear pew that limits boot space. You can get folding seats, but only as part of an option package.

What you're left with is a vehicle that stretches 5054mm in length, 1953mm in width and 1447mm in height, but that serves up rear seating for only two – albeit very comfortably – and, because of the electric battery and motor being housed at the rear, boot space of just 335 litres.

There is triple-zone climate control, and the rear seating is lounge-like and luxurious, while the up-front space is ample for two full-size riders, too.

There's no spare, with AMG's 'Tirefit' puncture repair system on board.

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).

It's not just what's under the bonnet, but what's at the rear axle, too.

But let's start at the front, shall we? Here, a familiar twin-turbo V8 engine lurks, producing a potent 470kW and 900Nm, which is fed through a nine-speed automatic, complete with paddle shifters and several drive modes, including the traction-limiting 'Race'.

But that is then joined at the rear by an electric motor with its own two-speed transmission, and which produces 70kW and 320Nm – or up to 150kW for 10-second blasts under heavy acceleration.

Combine both, and you're tapping into around 620kW and in excess of 1000Nm, enabling a sprint to 100km/h in just 2.9 seconds, and a flying top speed of 316km/h.

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.

Fuel efficiency is surprisingly impressive for a vehicle this big and powerful, with Mercedes claiming 7.7L/100km and 175g/km of CO2 on the combined cycle.

Helping that is a the 6.1kW battery, which delivers just 12km in all-electric driving range, but helps reduce overall fuel use.

This AMG is AC power only, meaning you can't recharge using fast chargers, but the brand says its secret trick is its ability to recharge itself using captured kinetic energy incredibly quickly – largely negating the need to plug in unless you want to unlock that EV range – with Merc suggesting that, on a race track for example, the battery will discharge and charge itself continuously as you're lapping.

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.

There's a lot of big numbers surrounding the Mercedes-AMG GT63S E Performance, but let me throw another one at you – 245km/h.

That was the high score I saw pop up on its digital speedo as the big and electrified Mercedes flew down the main straight at Sydney Motorsport Park (formerly Eastern Creek), before my courage ran out and my foot found the brake.

That kind of velocity is mind-bending in a vehicle this big, and so is the way that power is delivered, with the AMG's big brain deciding how and when to maximise power from the engine and electric motor to deliver a constant surge of torque that shoves you back, and the GT63S E Performance into the future.

But big acceleration is hardly surprising with that much power. What is a little more impressive is how easy this four-door supercar is to wrestle around a racetrack.

Sure, the feeling-out process is a little more involved, as you figure out how and when you'll feel the weight shifting, and as your brain struggles to compute how what's happening is even possible, but after a couple of laps the AMG settles into an easy, flowing rhythm that, while never feeling light on its feet, also doesn't feels like you're piloting a bus.

At least part of that is down to the wizardry on board, like the 'AMG Air Suspension', the rear-axle steering and the limited-slip diff, all of which combine to make the GT63S feel tighter and sharper than it would otherwise.

But it's also partly down to the prodigious power on offer – perfect corner entry and exits are less relevant when you have a cruise missile strapped to your right foot that doesn't just quickly make up for any driver errors, but shrinks the space between corners to the blink of an eye.

Yes, it's heavy, and there isn't much that's pure about the go-fast experience, but it left an ear-to-ear grin on my face, and isn't that priority one for any new AMG?

How does it drive on the road? That I don't know, as this was a track-only drive day. But we will get one on a proper test soon and let you know.

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 GT63S E Performance is covered by Mercedes' five-year, unlimited-kilometre warranty, and you can pre-pay your service costs to keep the prices down.

Service pricing for the electrified model is yet to be confirmed.

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.