Mercedes-AMG SL 55

Punchy new AMG-developed roadster is driven on UK road for the first time For an idea of how different the R323-generation Mercedes SL is to its predecessor, consider the press pack, which runs to nearly 20,000 words.A dissertation-length work, it contains an onslaught of information that explains Mercedes’ repositioning of the model from aristocratic two-seat tourer with sporting undertones to something much more muscular, aggressive and, according to at least one exec, with the basic ingredients to tempt people out of their Porsche 911 Cabriolets and Targas. Long story short, the SL has been properly AMG-ified.It starts with an all-new aluminium platform. The material used isn’t surprising, given the SL has since 2011 been constructed from lightweight aluminium, but this time the structure is dramatically more rigid (the old R231 was hardly a damp flannel, either) and the development has been undertaken not at Sindelfingen but by AMG in Affalterbach. That alone is quite the statement of intent, at least in dynamic terms, and the upcoming replacement for the Mercedes-AMG GT will inherit plenty of this new SL's hardware. The long-snounted roadster also now comes with front driveshafts and rear-axle steering, for added performance and agility, and returns to having a lighter fabric (rather than a metal folding) roof. Lastly, and for the first time ever, there are back seats. So the SL is overhauled, and has a new game plan.But is it any good on the road? We thought so when we drove the range-topping 577bhp, £176,000 Mercedes-AMG SL 63 in the US, where its ability to engage one moment and coddle you over distance the next seemed outstanding – even if at that price, in that balmy weather, and on those smooth roads, you’d absolutely expect as much. The less spectacular SL 55 driven here, on wintry UK roads, has an altogether tougher task.For one thing, and like its bigger brother, it’s hardly in bargain territory. For the £148,000 Mercedes-AMG asks, you could buy the faster-on-paper Porsche 911 Carrera 4 GTS and have enough change to get a Volkswagen Up GTI. At that price you might also reasonably expect the power output figure to start with a ‘5’ if not a ‘6’. Instead, the SL 55 makes do with 469bhp.However, less than outright top-end power, it's the easy-going sledgehammer manner of AMG’s twin-turbocharged M177 4.0-litre V8 that informs much of the car's personality, and 516lb ft delivered from only 2000rpm is pretty emphatic.  It means that while SL 55 lacks truly jaw-dropping performance, it is ready to shift itself at almost any speed and in any gear. This engine is decently free of lag, too, so the performance really is press-and-go. Unsurprisingly such effortless pace plays nicely into the car’s GT credentials, which are in general excellent, but for the ever so slight brittleness that creeps into the ride quality on poor surfaces. Perhaps the SL 63 - with its McLaren-esque, anti-roll-bar-less, cross-linked hydraulic damping system – will do better in this respect, though the SL 55, on traditional semi-active suspension, is hardly what you’d call rustic. With a comfortable, plush, cosseting cabin and free-breathing vertical body control, most of time it just gobbles up big miles without thought. It eats up B-roads with less natural ease but plenty of enthusiasm nonetheless. Traction is superb, to the extent that this chassis will take full power and torque in second gear on a cold, greasy surface. The agility-enhancing effects of the rear-wheel steering, which works in contrary motion to the front wheels at anything below 60mph, are also apparent, and impressively fluent. This is an easy car to place at speed and it gives you the confidence to chase the throttle and revel in that monster V8.As a luxury, cross-country, all-season GT of surprising precision, the SL 55 works well. And there are, of course, many, many chassis and engine modes that give the car pretty staggering breadth. But as a proper 911 rival? I’m not so sure. At almost 1900kg, the SL 55 is too heavy, and while clever in the way it manages its mass, the car can never escape its effects. You, the driver, are always aware of it, waiting for it to tug the nose off line through an unexpectedly tight corner, or for the body to fall a step behind what the road is doing. That neither of these things ever really happens is a mark of just how well sorted the SL 55 is, but the point is that you feel as though they might, and that's not so enjoyable.The electromechanical steering is also somewhat soulless compared with the electrohydraulic set-up in the AMG GT and the four-wheel-drive chassis can be a touch too neutral at times, though perhaps this is one of the car’s virtues. It depends what you're after. If material plushness and dynamic solidity are your priorites, you'll enjoy the Mercedes and love using it. But if you want a sports car that does more than hold you at arm's length, charming you superficially with its thumping engine and easy pace...So, altogether the SL 55 is an immensely capable car. Perhaps there are some unflattering interior plastics for this price point, and the fact that the wind deflector is manual not automatic is pretty unforgivable at this price, but in the main it's a complete product all right.So complete, in fact, that you might wonder whether it's trying to do too much. Fast and agreeable to live with the car might be, but the GT-leaning driving experience lacks bite and never really gets under your skin, or at least it didn't in an afternoon or two of driving on some of the UK's best roads. It’ll be interesting to see if the fire-breathing, more technically sophisticated SL 63 does better over here, or whether it too will feel built more with base-covering in mind than passion and focus.