Used Mercedes-Benz SL 2012-2020 review

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The Mercedes SL is perhaps the most splendid, single-minded luxury convertible in the world

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The Mercedes-Benz SL is a fascinating, enduring and exquisite contradiction of a sports car.

This two-seat convertible has a triumphant motorsport history that most sports car makers would consider priceless, and for the past decade or so – thanks to the work of AMG – it has ranked among the fastest and most powerful roadsters in the world.

A singular triumph. Not just one of the finest Mercedes on sale, but one of the most desirable cars period
Matt Saunders
Road test editor

And yet it’s become a car revered not for performance as much as opulent luxury, immaculate refinement and unparalleled usability. It’s a sporting convertible perfectly designed to appeal to the retired chauffeur in us all.

But Daimler has greater ambitions for this new version. The arrival of the AMG SL 63 models has reduced the average age of SL owners considerably, but Mercedes wants to lower it further by injecting greater response and dynamism into the SL’s character.

It has gone to great lengths to do that, by way of weight saving, body strengthening and powertrain overhaul – all of which we’ll cover in the following review. But have the impeccable manners of the grand old Mercedes convertible survived?

 

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DESIGN & STYLING

Mercedes-Benz SL rear

Having familiarised itself with the use of structural aluminium while producing the hand-built Mercedes SLS, the firm has taken the plunge by making the new SL its first series production car to be built predominantly from the stuff.

The state-of-the-art superstructure contains chill-cast, die-cast, stamped and extruded aluminium parts, as well as some magnesium and hot-formed galvanised steel. The components, joined using six different methods, contribute to a body-in-white weight 25 percent less than it would be in steel, along with a 20 per cent boost in static torsional stiffness.

SL is impressively light compared with most grand drop-tops
Matt Saunders
Road test editor

Daimler’s determination to make this new SL worthy of the ‘Super Light’ billing has driven its engineers to find weight savings all over the car. Having taken 15kg out of the roof, 11kg out of the seats, 11kg out of the front suspension, 4kg out of the electrics, 4kg out of the stereo, 4kg out of the front brakes and even 250g out of the wheel nuts, they’ve delivered the SL500 at a claimed 1785kg.

Our SL 500 test car, brimmed and fitted with £19,000 worth of options, weighed 1815kg. Impressive, considering that most grand drop-tops comfortably exceed two tonnes. An entry-level Mercedes SL 400, by comparison tips the scales at 1735kg.  

The car’s multi-link chassis is now almost exclusively forged aluminium and features valve-controlled adaptive dampers as standard. Those wanting a more sporting set-up can opt for the stiffer springs, dampers and anti-roll bars, and reduced ride height of the AMG sports package of our test car.

Mercedes’ Active Body Control suspension is also an option. It’s a self-levelling set-up that replaces the conventional spring struts and stabilisers with active hydraulic struts that continuously adjust in terms of spring length and roll stiffness. Contrary to popular misconception, air spheres are not involved.

Even after all that, the SL 500’s new aluminium V8 is far from overshadowed. At once 22 percent more fuel-efficient, 12 percent more powerful and with 32 percent more torque than the old SL’s normally aspirated 5.5, the new car’s 4.7-litre engine uses twin parallel turbochargers to produce 448bhp and a formidable 516lb ft.

It drives the real wheels through Mercedes’ latest 9G-Tronic Plus nine-speed torque converter automatic gearbox. Other engine options include a 3.0-litre V6, badged SL 400, an a pair of range-topping AMG-tuned models in the form of the V8 SL 63 and the V12 SL 65 AMG, both of which use an AMG-tweaked seven-speed auto transmission.

INTERIOR

Mercedes-Benz SL dashboard

Nestled in the new Mercedes SL, you’re seated so far from your passenger that it’s hard to believe this is a two-seat roadster at all. In terms of lateral cabin space, the SL is more like a limo. It’s even wider this time around, having grown by 57mm in girth, and provides acres of elbow and shoulder room.

Nevertheless, a pair of seats is all you get. The cabin, however, provides lots of room for two occupants, and not just in terms of occupant space. There’s a large storage cubby at the base of the centre stack, a roomy armrest cubby, a third covered cubby behind that and a lockable box immediately behind the passenger seat that is large enough to keep your valuables secure with the roof down.

Its sat-nav - complete with real-time traffic warnings - is very advanced
Matt Prior
Editor-at-large

The new SL’s door pockets are extra-long (a consequence of the bass speakers for the audio system migrating to the footwells), and you can afford to sacrifice some legroom to accommodate soft bags behind the seats should the car’s boot capacity come up a bit short. But with 504 litres of space back there at a maximum, and room enough for a couple of travel cases even with the roof down, we’d say it’s unlikely to.

A few testers found some of the styling a little flashy – the ‘SL’-branded gear selector, for example, lacks the classy reserve that has characterised this car in the past. The luxuriant cabin materials and flawless fit and finish are impressive, even by Mercedes’ standards. You get plenty of equipment as well with both the SL 400 and SL 500 coming fitted with an AMG Line trim, while the AMG models get their own equipment list.

The entry-level SL 400 gets 17in alloy wheels, electrically folding and badge projecting wing mirrors, sports suspension, an aggressive bodykit, LED headlights and a panoramic sunroof on the outside, while the SL 500 gains 19in alloys. Inside both get dual-zone climate control, leather upholstery, electrically adjustable sports seats and a wind deflector, all as standard.

Upgrade to the AMG 5.5-litre V8 SL 63 and you'll find a beefy bodykit, a limited slip differential, sports suspension with active body control, a rorty exhaust system and heated front seats, while the V12 SL 65 behemoth benefits from rolling on 19s on the front and 20s on the rear, a front splitter, a carbonfibre bonnet, ventilated seats and a Bang & Olufsen audio system, alongside Mercedes' Driver's Assistance pack which includes active blind spot, rear-collision and lane assist, adaptive cruise control and autonomous braking. All this safety features are available on the AMG Line trimmed SLs and the SL 63 for an additional £1695.

Generally, however, you can’t help feeling superbly comfortable, obscenely well provided for and generally very fortunate indeed to be inside this car.

ENGINES & PERFORMANCE

Mercedes-Benz SL side profile

If you feel fortunate to be inside the Mercedes SL at all, those who like impressive performance will feel luckier still to be in a 500 when the throttle is flattened. At our test track, pressing the right pedal into the carpet was enough to propel the SL 500 to 60mph in 4.3sec – quicker than the previous SL 63 – and on to 100mph in less than 10 seconds. By a kilometre it’s doing 150mph. Make no mistake, this is premier league roadster performance.

But SL traditionalists need not fret, either. You only hear the 500’s engine should you want to and you need only feel the limits of its performance if you ask for them. The rest of the time the SL is happy to sit back and do the cruising that you’d expect of it. Locked into top gear, it’ll still pull from 50 to 70mph in 6.5sec. That’s a bit of a difference from the 2.1sec it wants in third gear, but amply impressive given that acceleration from 50mph in top starts from around 1250rpm.

At cruising speeds, you'll easily see the good side of 30mpg
Matt Prior
Editor-at-large

And with it, it’s as utterly tractable and refined as you’d expect. At idle, cabin noise is restrained to just 41dB, which is in line with most executive and luxury saloons. Isolation is really terrific, too, although some road noise enters the equation later.

Not so long ago, a 4.7-litre turbocharged motor making 92bhp per litre would result in its owner being on first-name terms with their local petrol station proprietor. However, relax into a cruise and the SL 500 will see you good for the other side of 30mpg, while we’d expect most owners to better our average return of 24.1mpg. Even if they don’t, they’ll still be looking at a credible 400-mile range between fills.

Sitting beneath the SL 500 is the SL 400, powered by a turbocharged 3.0-litre V6. Moreover, because of the SL 400's 87bhp power disadvantage against the SL 500, its power is more usable on UK roads. And 361bhp means it's still capable of 0-62mph in less than five seconds.

The range-topping SL 63 delivers quite ludicrous performance. Its reduced kerb weight over the previous SL combined with a twin-turbocharged 5.5-litre V8 means a torque-to-weight figure of 375lb ft per tonne, 89lb ft more than even the SLS AMG. Allied to 577bhp, this is enough for 0-62mph in 4.1 seconds. If that's not quite enough for you, the even more potent SL 65 AMG offers up 0-62mph in just 4.0sec, thanks largely to its 621bhp 6.0-litre V12.

The SL braked with conviction; anything that takes less than 45 metres to come to a standstill from 70mph is a first-class stopper. Its brakes also resisted fade admirably on the handling circuit.

RIDE & HANDLING

Mercedes-Benz SL cornering

We’ve got mixed feelings here. And, we suspect, given the other Mercedes SLs we have driven (although admittedly abroad), there is a reason for them. The optional AMG suspension as fitted to our test car as part of the Sports Package drops the regular SL’s ride height by 10mm. This, coupled with 19-inch alloys wearing 30-profile tyres at the rear, brings a rather firmer set-up to the SL than we (and we imagine most customers) were entirely expecting.

Most of the time, things are fine. The SL deals with little surface imperfections and larger crests and dips well, although it’s better across the former in its softer damper setting while having tighter overall body control in the firmer set-up. But it doesn’t matter whether you pop the dampers into their Comfort or Sport modes across the more sudden bumps and potholes that really jar the SL’s body. It is one of the few occasions during which you will perceive any lack of body stiffness.

Potholes can nreally jar the SL's body
Matt Saunders
Road test editor

Otherwise, the SL feels impressively rigid, particularly with the folding hard-top up. The steering feels isolated from bad roads and, even with the roof down, the rear-view mirror rarely gives a view-distorting tell-tale shimmy.

Roof down, the SL feels just like a classy roadster should: a wind-in-the-hair experience, without your hair actually getting that windy.

And in extremes? The SL is as entertaining as you’d reasonably expect it to be, but with a few peculiar, stability system-induced movements to its body mid-corner. It’s no Porsche 911 cabriolet, but it retains more agility and adjustability than, say, a Bentley Continental GTC V8 (which, admittedly, has seats for an additional pair of occupants).

Despite its extra power, the SL 63 and SL 65 handles very similarly to the 500. Grip levels are higher thanks to its larger tyres and wider tracks but the steering still lacks feel.

Predictably, given its lower kerb weight of 1685kg, the SL 400 delivers a sharper turn-in than the larger-engined models. It is probably the sweetest-handling of every SL. But it's definitely the case that those wanting a more laid-back experience should avoid the optional AMG suspension.

MPG & RUNNING COSTS

Mercedes-Benz SL

Exclusivity is a core part of the Mercedes SL mystique, and mere acquaintance with this car leads you to expect it to cost more than the class average.

And it does, but not disproportionately more, considering the performance and refinement on offer and the standard equipment list. Adaptive dampers, voice-activated satellite navigation, intelligent bi-xenon headlights and the like aren’t items that usually come for free, even at this rarefied level.

Predicted residual values are a worry for future SL owners
Matt Saunders
Road test editor

More concerning than the asking price is the residual value forecast made about this new SL by Autocar’s sources, suggesting it will fare slightly worse over three years than even a Jaguar XK – a car that’s already long in the tooth.

That will be offset a little by a good emissions performance for those running an SL as a company car – although very few people will get the chance to do that.

It’s a good job depreciation is something SL owners are already well used to.

 

VERDICT

Mercedes-Benz SL rear quarter

After so many years of success, some might question the wisdom of Mercedes’ decision to tinker with the dynamic DNA of the SL. But we don’t.

While it’s true that our test car’s uncompromising chassis spec meant it didn’t glide over every surface with the impeccable calm of other examples we’ve tried, it was still a bubble of ample cushioning, soothing quiet and blissful freedom from the normal motoring experience.

Still totally unique, now even more appealing — but get the spec right
Matt Prior
Editor-at-large

The less agreeable news is that the AMG chassis settings don’t turn the SL into an outstanding driver’s car. Despite its formidable performance, you’ll still get more vivid kicks in a couple of other grand convertibles we could mention.

And yet, for everyday driving, the SL’s opulent luxury, refinement and ease of use could be just as convincing as its rivals’ vivacity and fleeting agility. Maybe more so. Long live the legend.

 

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.