Mercedes-AMG SL 63 E Performance review

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Seventh-gen roadster adopts latest hybrid tech for next-level performance boost

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Mercedes' decision to twin the seventh-generation SL with its second-generation Mercedes-AMG GT has opened the door to a whole new level of performance for the luxury roadster. And charging through that gap is the plug-in hybrid Mercedes-AMG SL 63 S E Performance.

The SL is already available with a turbocharged 2.0-litre four-cylinder engine with 416bhp (called the Mercedes-AMG SL 43), as well as with a twin-turbocharged 4.0-litre V8 powerplant developing either 469bhp (in the Mercedes-AMG SL 55 4Matic+) or 577bhp (in the SL 63 4Matic+). But even by the standards of those sibling models, this version is a big step up.

The S E Performance's twin-turbocharged 4.0-litre V8 and electric motor combo, worth a combined 805bhp, makes it the most powerful SL since the 'R230'-generation SL65 Black Series of 2008. Its hybrid system is also used by its fixed-roof sibling, the Mercedes-AMG GT 63 S E Performance.

Performance PHEVs capable of fewer than 10 miles of EV range are few and far between. But the SL 63 S E Performance does go toe-to-toe with the likes of the PHEV Bentley Continental GT as well as the hybrid Porsche 911.

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DESIGN & STYLING

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mercedes amg sl 63 03

The 'R232' generation of SL was a real watershed moment for the model, given that it's twinned not with a limousine but with a sports car.

The range-topping PHEV model mates a 604bhp 4.0-litre twin-turbocharged V8 with a 201bhp electric drive motor, for combined system peaks off 805bhp and 1047lb ft.

Titanic-looking outputs, those. However, since Mercedes-AMG's performance hybrid system uses an electric motor that drives into the rear differential via its own two-speed electric motor, it becomes a little conditional whether all of that power and torque is available to this car all of the time; and if not - depending on selected gear and prevailing cruising speed - precisely how much of it may be. 'P2'- and 'P3'-style hybrid systems (in which the electric motor drives into the same gearbox as the combustion engine) make it simpler to calculate 'total system' power and torque, but this car's 'P4'-style set-up is more complicated. Not so complicated, however, that Mercedes can't claim a pretty eye-watering 2.9sec 0-62mph sprint for the car.  

Powertrain aside, the SL 63 S E Performance doesn't change all that much compared with other SL models; it simply gets as standard all the active suspension, braking and steering tech you can choose as options on other SLs. So here you get steel coil springs with active anti-roll bars and hydraulically interconnected dampers, four-wheel steering, and carbon-ceramic brakes for no extra cost.

 

INTERIOR

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mercedes amg sl 63 06

Like other SLs, and unlike several of its generational forebears, the SL 63 S E Performance comes with a folding cloth roof that can be lowered or raised at lower speeds. Similarly, while older SLs spent decades as strict two-seaters, this one has sprouted occasional back seats, although they're very small. They'd work as a storage space for small suitcases, but even younger children would quickly become uncomfortable back there.

The car's cloth roof, when folded, eats less into available boot space than the old folding metal one, and in other SLs that leaves a fairly useful 213-litre boot. But the biggest difference here with the 63 S has to do with the PHEV batteries: they rob the car of 103 litres of boot capacity, leaving just 110 litres overall. With a PHEV's obligatory charging cable bags riding in that space as well, there's just enough room for a medium-sized soft rucksack; larger suitcases must therefore ride in the cabin.

That's not a great look for any luxury GT. Longer-lived SL regulars might well have preferred a two-seat cabin with more boot space, while those to whom the extra usability of back seats is supposed to appeal might well wonder what they're really getting when those 'seats' might just as well be a luggage rack. We can't see anyone being satisfied with the SL 63 S's meagre boot.

The car's wider cabin is more impressive, though. A fine, low driving position is well supported by the driver's seat, and controls are arranged simply on the steering column and wheel spokes. Perceived quality is a cut above Mercedes' less impressive standard for its more workaday models, but it'll be a little too glossy, ritzy and chintzy to suit some preferences.

The car's touchscreen infotainment system is portrait-oriented and can be adjusted for angle of inclination so it doesn't reflect the sunlight when the roof is lowered (a clever touch). It's quite easy to navigate when driving, thanks to a cursor controller on the left spoke of the steering wheel, while ADAS functions (such as speed limit reminder buzzers) are easy to access and deactivate.

 

ENGINES & PERFORMANCE

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mercedes amg sl 63 02

This SL is quite a multi-faceted car to drive. Electric running is limited - if you string the drive motor out to cover eight miles before the combustion engine takes over, you'll have been driving very conservatively indeed. But this car is certainly a more relaxing one to drive around town than it might be thanks to its hybrid system. It has plenty of electric performance at town speeds, and if you do want a break from the attention-attracting woofle of an AMG V8, it's nice to have the option of silent running to hand.

On open roads the combined reserves of internal combustion engine and electric motor give this car towering performance; select Sport + or Race driving mode and, with the roof lowered, the deep and unfiltered baritone blare of the V8 isn't short on audible appeal either. The SL 63 S E Performance feels genuinely supercar-fast and has huge and instantly accessible torque - with the snarling V8 there to keep you engaged in gear selection and planning ahead, in a way that an equivalent EV would fail to do.

This is a great powertrain when you need to make pedestrians aware of your presence, when entering side roads for example. You'll tend to be in electric mode here, but flicking the drive mode selector to Sport starts the V8 in an instant - and it's loud enough to make anyone check over their shoulder.
Matt Saunders
Road test editor

The petrol-electric drivetrain not only brings an added 228bhp and 457lb ft over the existing range-topping SL 63 4Matic+ but also adds 225kg to the kerb weight, at 2195kg. In terms of performance, however, that weight’s not a limiting factor. The SL 63 S E Performance balances its dual role as traditional sun-seeking upmarket roadster and rapid open-top sports car with aplomb.

RIDE & HANDLING

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mercedes amg sl 63 05

With around 30% less torsional body stiffness than an equivalent Mercedes-AMG GT, together with a narrower front track and 275-section front tyres, the SL possesses a slightly more comfort-oriented driving character than the GT 63 S E Performance, which is clearly sharper to drive. It’s a predictable move and fully in keeping the positioning of the SL.

This is a heavy car indeed to be rolling on conventional coil springs. In tandem with the active anti-roll and four-wheel steering systems they provide effective body control and handling poise at normal road speeds, but when you stretch this car's legs on a challenging B-road you begin to find the limits of its capabilities: the ride - already noisier and clunkier than other SLs on account of the overall mass and the stiffness of the tyre sidewalls needed to support a near-200mph top speed - gets more abrupt and percussive, while the ability to keep control of its mass over vertical inputs also deteriorates.

Lateral grip and roll resistance survive quicker driving more steadfastly, but neither is quite convincing enough to reassure you that this car belongs at fast B-road speeds. Mercedes certainly doesn't tune the steering for much tactile feel - this is a luxury GT, remember, so feedback isn't its top dynamic priority - while the electrically bolstered rear axle doesn't make for the most predictable or progressive limit handling charactertistics.

With the windows up, wind buffeting within the cabin is well controlled – with a top speed of 197mph, the roof really ought to be hurricane-proof. Either way, it certainly keeps out wind noise on the motorway quite well.

 

MPG & RUNNING COSTS

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mercedes amg sl 63 01

A 4.8kWh (usable capacity) lithium ion battery resides in the boot, giving the most powerful SL of all time a claimed electric range of up to – drum roll, please – 8.1 miles.

In real-world use, it's more like 6-7 miles, depending where you're driving. And that's certainly not enough to have a meaningful effect on how much fuel your 800bhp Mercedes is likely to use. If you keep it on the high side of 25mpg, you'll be doing well.

Mercedes is asking for within a whisker of £190,000 for this car, for which it ought to be the best SL in the range by some distance. As an 800bhp luxury PHEV convertible, it has few natural rivals (a Bentley Continental GTC Hybrid costs another £60k), which may have given Mercedes a little too much latitude to price this car to its own liking. However you explain it, Mercedes-AMG is asking an awful lot here for the top-of-the-line SL, and it certainly isn't delivering a car without notable compromises.

VERDICT

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mercedes amg sl 63 04

This SL 63 S E Performance is an interesting technical showpiece for Mercedes and impressive to drive in some ways - but it's compromised as a luxury grand tourer in a couple of notable respects.

The touring practicality you would expect of a near-£200,000 Mercedes convertible is missing here. The car's 110-litre boot is a major shortcoming and would be unlikely to swallow your weekend luggage; and by the time your bags have overspilled into the back seats, you may wonder why Mercedes bothered to make this car a plus-two at all.

It also has some refinement issues you might hope your dream Mercedes luxury convertible would be without: a noisy and at times intrusive ride, for one, and an all-round driving experience that promises quite a lot more than it eventually delivers in terms of driver engagement.

This car's titanic performance level is certainly enticing, but there's only so much of it you can use on the road. The V8's audible appeal is a great fallback position - but its richness is no more convincing here than in an SL 55 that you could buy for £45,000 less.

 

Matt Saunders

Matt Saunders Autocar
Title: Road test editor

As Autocar’s chief car tester and reviewer, it’s Matt’s job to ensure the quality, objectivity, relevance and rigour of the entirety of Autocar’s reviews output, as well contributing a great many detailed road tests, group tests and drive reviews himself.

Matt has been an Autocar staffer since the autumn of 2003, and has been lucky enough to work alongside some of the magazine’s best-known writers and contributors over that time. He served as staff writer, features editor, assistant editor and digital editor, before joining the road test desk in 2011.

Since then he’s driven, measured, lap-timed, figured, and reported on cars as varied as the Bugatti Veyron, Rolls-Royce Phantom, Tesla Roadster, Ariel Hipercar, Tata Nano, McLaren Senna, Renault Twizy and Toyota Mirai. Among his wider personal highlights of the job have been covering Sebastien Loeb’s record-breaking run at Pikes Peak in 2013; doing 190mph on derestricted German autobahn in a Brabus Rocket; and driving McLaren’s legendary ‘XP5’ F1 prototype. His own car is a trusty Mazda CX-5.