Mercedes-Benz SL review

Mercedes has been on to the Formula 1 department, so there are various aero widgets to improve stability, reduce drag, and optimise cooling. At the front two-piece active aero Air Panel uses electronically actuated louvres to hustle air either into cutting drag or into maximum cooling mode. The bootlid spoiler dances among five different positions depending on speed and whether you're cornering or braking.

The chassis mixes aluminium, steel, magnesium and carbon fibre composites to promote greater rigidity while keeping things – theoretically – light. Overall, the bodyshell weighs 270kg; it’s a shame Mercedes couldn’t get the rest of the car on a diet. Most of the complex chassis systems on the SL 63 and 63 hybrid are there to mitigate the weight, while themselves adding… more weight.

Tell me about the four-cylinder’s turbo…

The entry-level SL 43 adopts a form of MGU-H turbo tech from Merc's F1 car. An electric motor is tucked into the shaft of the turbo, so that at low revs, before the exhaust gas turbine has spooled up, the motor drives the intake compressor wheel, pretty much killing lag. It's juiced by a 48-volt mild-hybrid system whose motor-alternator can itself provide another few horses direct to the crank, at least in brief bursts.

It's a quick car, if maybe not quite as quick as a £100k sports car could be. Still, 0-62mph in under five seconds is fine, and the transmission makes the best of it. The engine has – as its technology promises – a strong, lag-free mid-range but revs freely too. There are more charismatic-sounding engines out there, not least in the SL's nemesis the 911, but you absolutely mustn't imagine that the 43 is an SL ruined by a workaday engine.

But what if I want a proper V8?

The V8 from so many other AMGs is revised here with a repositioned intake, exhaust and other external components, and complex three-layer cooling. The 63s benefit from active engine mounts to isolate unwanted vibrations and promote a more relaxed demeanour when you're cruising, but sharpen up when you're going hard. AMG’s nine-speed MCT transmission has a wet clutch rather than a torque converter, which reduces weight and has lower inertia to deliver faster shift times.

You collect just over 60 horsepower going from 43 to 55, and then over 100bhp from 55 to 63. And even though the 63 is heavier than the 43, you soon realise you've got an engine that sweeps all before it. There's not the sheer teleportation of some fast EVs, but there's relentless force. And a rock 'n' roll accompaniment with it, but fortunately not as antisocially loud as some other AMGs.

And how’s the hybrid powertrain?

Well, it brings 805bhp and a 0-62mph time of 2.9 seconds, so you won’t be surprised to hear that it’s absolutely rapid. The electric motor is paired with a two-speed electric gearbox with the whole setup mounted under the boot floor and all of the power sent to all four wheels. It accelerates like a runaway freight train and weighs about as much as one too.

And yet, while the non-hybrid 63 is a confused mix of sports car, muscle car and grand tourer, the hybrid SL perhaps makes a little more sense. It only has a small battery, but it’s able to recoup plenty of energy through regen so you’ve always got max power available and always got a decent bit of e-range to creep through town. Then, once you’re out of the city limits, you’re able to wake the V8 and travel at huge pace. The E Performance feels like more of a big GT and it’s all the better for it.

How can the SL be both sporty and comfy, as they claim?

The 43 uses straightforward coil springs. The 55 gets adaptive dampers with a choice of programmes. The 63s gain active anti-roll stabilisation with hydraulically connected dampers. The 55 and 63s get four-wheel steering as well as electronically controlled four-wheel drive. The 63s also have an active limited-slip diff.

New five-link suspension at both the front and rear should help both refinement and precision. That's a whole lot of engineering, both mechanical and electronic. It’s also highly configurable, with multiple modes for the powertrain, suspension and drift-control system, called AMG Dynamics.

On smooth, dry roads the V8s are impressively agile and grippy. If you must, they'll push their tail out if you're in the right electronic dynamics mode and have plenty of space to play. Even in the wet the combination of four-wheel-drive and electronic systems keeps them secure, a big change from the old AMG GT.

But it's very hard to sense where the limit lies, so they can feel nervy. The four-wheel steering system is designed to add agility in sharper bends, but sometimes it can catch you out by needing more or less steering input than you expect. Meanwhile the adaptive damping systems get caught out by British roads, bringing a brittle sharpness to certain kinds of bumps. Overall then, the V8s lack that feeling of connection to make you fall in love with a sports car.

What about the SL 43?

With passive suspension, and no 4WD or 4WS, and a lighter nose, the 43 is a different thing. It just feels more fluent through bends, and the steering has a more natural feel, because it's simpler and because it's fighting less mass. The ride is consistently fluent too. Not soft or floaty but disciplined without being harsh.

As a touring car, it suffers road noise and some roof-up wind noise from the top of the pillars. As an open car it's hugely impressive, with little buffeting even at motorway speeds if you have the windows up, and volcanic heating for the seats and steering wheel plus the Airscarf system that lovingly caresses the back of your neck with warm air.

There’s also the same vast suite of driver assistance programmes as you’ll find on other high-end Mercs, although some are to be found only in an options package. The lane assist is much less intrusive than elsewhere.