In-depth Reviews

Mercedes SL convertible

"The Mercedes SL is a convertible two-seater sports car with a focus on comfort over handling. It does a fantastic job"

Carbuyer Rating

3.6 out of 5

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Owners Rating

4.5 out of 5

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Pros

  • Amazing performance
  • Comfortable ride
  • Quite practical

Cons

  • Expensive to buy
  • High running costs
  • Not very exciting to drive

The Mercedes SL is a stalwart of the luxury roadster class, and is rather unique in its appeal. It’s a big car, with a powered retractable hard-top and is aligned towards the top of the Mercedes range – selling alongside the Mercedes S-Class convertible.

The latest Mercedes SL cabriolet has a state-of-the-art aluminium bodyshell and a choice of four engines. It’s lighter, faster and more fuel-efficient than its predecessor, and also also sharper to drive. With the launch of the Mercedes-AMG GT sports car, The SL range has been brought into line with the image of the AMG performance arm of Mercedes. As a result, it’s now either available as an AMG Line or as a full-on AMG.

There are two AMG-Line SL models: an SL400 fitted with a 367bhp 3.0-litre petrol V6 and an SL500 with powerful 445bhp V8. They feature 19-inch AMG alloy wheels, AMG styling components, lowered, stiffened sports suspension and full LED headlamps. There’s no shortage of conveniences, either, will all models featuring Mercedes’ impressive COMAND infotainment system (with online capability and DAB radio), leather memory seats, front and rear parking sensors and many other gadgets.

The range flagships are the pure AMG models. The AMG SL63 boasts a 577bhp V8 and at the very top of the performance tree is the AMG SL65 with its 621bhp 6.0-litre V12.

MPG, running costs & CO2

Costly to run

With a lighter body and more efficient engines, the current Mercedes SL isn't as expensive to run as its predecessors have been. Mercedes claims the SL400 can achieve 36.7mpg, while CO2 emissions stand at 175 grams per kilometer, which just squeezes it into the £210-a-year road-tax bracket. The V8-powered SL500 model manages 31.4mpg and CO2 emissions are 205g/km, lifting road tax to £205 per year.

The SL63 and SL65 AMG models are hugely powerful and cost a lot to run as a result. In the SL63, CO2 emissions stand at 234g/km for £500 road tax, while the SL65 emits 279g/km of CO2 for an annual bill of £515. The SL63 has an official fuel consumption figure of 28.0mpg, while in the SL65, the best you can hope for is 23.7mpg.

Engines, drive & performance

Impressive performance, but more focused on comfort than handling

The days are gone when an entry-level Mercedes SL felt underpowered. Today, even the SL400 has a twin-turbocharged engine and can manage 0-62mph in 4.9 seconds. It’s a smooth engine and sounds great. It’s also not much slower than the £10,000-more-expensive SL500, which takes 4.3 seconds to accelerate to the same speed.

The Mercedes SL is available in four versions: SL400, SL500, AMG SL63 and AMG SL65. The SL 400 is powered by a twin-turbo 3.0-litre V6, the SL500 gets a twin-turbo 4.7-litre V8, the SL63 uses a twin-turbo 5.5-litre V8, while the SL65 gets a huge 6.0-litre V12 engine.

Stepping up from the SL500 to the SL63 AMG you could be forgiven for wondering if the extra cost is worthwhile for a scant reduction in acceleration time to 4.1 seconds, particularly as all SLs are electronically limited to the same 155mph top speed. However, the SL63 is a completely different animal, from the way it feels to the sound it makes.

It’s very easy to break traction and spin the wheels from rest unless you’re delicate with the throttle. Tread sensitively, though, and the rear wheels will bite the road and propel you with astonishing accelerative force, with the car making a great noise at the same time.

The same is true in corners, where heavy-handedness can easily result in the car spinning – it pays to keep the traction control engaged to maintain grip.

In a way it’s not surprising that Mercedes allows the SL to have its own unique feel – that way it can be a companion to the AMG GT rather than a rival. However, we find the steering is a little too light and vague to build driver confidence. We were also disappointed by the way the SL63 rides.

On bumpy roads, you feel every shock, either through the seats or the bodywork, which shakes and vibrates whether the roof is in place or removed. This isn’t the body flexing – it’s because the car is set up so stiffly that there’s no way of these impacts being absorbed. Not only does this make things uncomfortable, but it can also get in the way of using the engine to its fullest.

There’s a system called Direct Select that enables the car’s setup to be adjusted and you can set the suspension to be as soft as possible without restricting the engine’s output – but this feels like a compromise. It’s a lot easier to drive fast in the AMG GT.

However, many prefer to simply lower the roof and cruise, listening to the exhaust rumble, crackle and howl, and for that the SL63 is perfect, dispatching long motorway journeys with unruffled ease.

For those who aren’t content with the barely controllable power of the SL63, the 621bhp SL65 can get to 62mph from rest in four seconds flat and is uncannily smooth to drive. However, it's actually much heavier than the SL63, and therefore doesn't feel much quicker than that car in action, as well as having further dulled handling responses.

Those looking for easily-accessed driving fun would be bettter looking at a Mercedes-AMG GT, Porsche 911 cabriolet or Audi R8 Spyder. However, there’s no denying that classical good looks and sheer top-down glamour of the SL will always have an appeal.

Interior & comfort

The most comfortable two-seater convertible on the market

The Mercedes SL is available with either a lowered stiffened sports suspension on AMG Line models or an AMG-optimised version of Mercedes’ Active Body Control (ABC) system. Previously there was a standard steel-spring suspension, which offered better ride quality, but that’s no longer available.

The sports suspension is rather firm, so buyers in the hunt for comfort would be well advised to order the ABC system, which enables the damping to be set in a softer mode.

Passenger comfort is also excellent in the SL, with good sound insulation meaning barely any wind or engine noise making its way in. With the roof down, buffeting is kept to a minimum.

All models now include 19-inch wheels, and this has gone some way to increasing road noise on the latest cars.

Practicality & boot space

Clever touches and a large boot make for surprising practicality

Folding hard-top convertibles are far from the most practical cars on the market, but Mercedes has done a good job with SL, which offers 504 litres of boot space. If you lower the roof – a process that takes 20 seconds – that's reduced to 364 litres. To help access to the boot when the roof is down, it lifts out of the way when you open the bootlid.

A practical feature allows you to swing your foot underneath the rear bumper to open and close the boot if your hands are full.

Reliability & safety

Reliability shouldn't be an issue and safety is top-notch

The SL itself doesn’t have a current rating for reliability as too few owners have participated in our annual Driver Power survey for it to rank.

It’s a product of Mercedes-Benz, which as a brand finished in 12th position in our 2016 survey, with customers enjoying its cars’ build quality, ease of driving and on-board technology. However, they disliked the running costs and poor reliability of some models. Of course, with Mercedes offering such a broad range of vehicles, not all praise or condemnation applies to every model.

SL safety is top-notch thanks to systems that warn you if you're tired, help you to change lane safely and even brake for you to prevent a collision. The SL hasn't been crash-tested by Euro NCAP, but we'd expect a five-star rating if it was.

Price, value for money & options

Expensive, even compared to overpriced rivals

The Mercedes SL is a rather expensive car to buy – even when you compare it to the other cars in its class. It's competitive with the BMW 6 Series convertible, however, and depreciation doesn't seem too bad at the moment, so you shouldn't lose too much when you sell it on.

However, as it represents a leap of almost £100,000 over the cost of the already-impressive SL400 entry-level model, it’s impossible to describe the SL65 AMG version as anything approaching good value for money.

The SL400 and SL500 AMG Line models feature Apple CarPlay, sat nav, climate control, DAB digital radio and Bluetooth as standard. Notable options worth taking include the Active Body Control (ABC) adjustable suspension system – expensive at over £3,000, but markedly improving ride quality. For £105 you can get an increased-capacity fuel tank and £1,900 gets you a ‘Magic Sky Control’ glass panel in the folding hard-top roof, which uses an electrochromic system to turn opaque at the touch of a button.

The Bang & Olufsen BeoSound AMG Surround stereo is fiendishly expensive at £5,000, but comes as standard equipment on the SL65. However, even this generous gesture can’t make that car good value.

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