That name's quite a mouthful, isn’t it?
Mercedes-Benz SLR McLaren Roadster is indeed a tongue twister. And make sure you get Merc and McLaren the right way round, otherwise the men from Germany will get all antsy.
Thus the name pretty much sums up the genesis of this car: from coupe (SLR), to hardcore coupe (the 722), and now to convertible. And the convoluted name reflects the machinations behind the scenes: the relationship between Woking and Stuttgart has been tense, to say the least, as the two companies have battled over their vision for the car.
The open-top is the latest collaboration between the British and German engineering giants, and a last-ditch attempt to make the SLR a success. We hear that sales have fallen far short of expectations; around 1200 coupes have been built at Woking since 2003, suggesting that the original 3500 target in its seven-year lifecycle is somewhat unrealistic.
So what has been the outcome of this bickering?
McLaren wanted an F1 successor; Mercedes wanted, and claims it got, 'the ultimate 21st century GT'. The actual result is a compromise, and one that is less than the sum of its parts. The engineers at Woking have given the SLR a carbonfibre tub, double wishbones all round, and an air brake. Stuttgart has added an automatic gearbox, and all sorts of heavy luxuries and sound-deadening that have made the SLR a bit of a porker at 1825kg.
For those that thought the original coupe was too soft, there's the 722 edition with more power and less weight. And now we have the poseur's version, the convertible with a canvas hood and an even barmier price tag. Yes, the rag-top is going to cost the thick end of £350,000

So is this Roadster any better?
In a word, no. It’s still a compromise but for now let’s get to details of that roof. Whilst it’s no fingernail-breaker like the Lamborghini Murcielago Roadster's, neither is it chic sophistication. First you have to twist a rather stubborn handle, and then push the whole roof assembly upwards. Only then do the electronics take over and lower the roof in 10 seconds.
Apparently a fully automated roof top would have added 8kg to the car, and raised its centre of gravity. Sounds like a dubious excuse to us. Either the system was prohibitively expensive, or McLaren won the day. But really, is the type of person who is going to buy this car going to notice such a difference?
A rigid tonneau cover was also vetoed, meaning there are a few unsightly gaps once the roof has folded away. But fear not, because should you live in a country where you will drive with the roof down all year round you can order some special panels. For a small fee, of course.
Is this the fastest and most exclusive convertible money can buy?
With 612bhp you would certainly hope so, but the Pagani Zonda Roadster and aforementioned Lambo could claim to be faster. Or you could purchase a Rolls-Royce Phantom Drophead Coupe and spend the £45k you saved on something nice.
Perhaps tellingly, the Mercedes-Benz USA website doesn’t let you compare the SLR to the Ferrari 599, but as a driver’s car, the Italian has the Anglo-German roadster licked. But for now, there’s no open-top 599, and it can’t compete with the SLR’s sledgehammer 575lb ft.

Ah yes, tell me about that engine
It’s a relatively simple three valve per cylinder, 90deg V8 with a belt-driven supercharger. And one of the world’s great engine noises. The engine clears its croaky throat before erupting into a muscle car V8 bellow overlain with tough supercharger whine.
Headline figures are 612bhp at 6500rpm, 575lb ft on tap from 3250rpm-5000rpm, 0-62mph in 3.8 seconds, and a hair-ruffling V-max of 207mph. Oh, and 14.5mpg average, if you're counting.
That blower is fed through an air intake which leads from the three-pointed star on the grille and back to the engine mounted behind the front wheels. This front-mid-engined layout means 50:50 weight distribution, boding well for handling balance.
Stop teasing us. What’s the SLR Roadster like to drive?
Dominated by that epic engine, which is probably a good thing as it takes the focus off the other problems. The steering rack is from an A-class, believe it or not, and the lack of variable power assistance means no difference in weighting at 20mph and 200mph. The result? Steering is hyper-sensitive, yet lacking any real feedback.
This is confounded by the SLR’s ride. The car follows ridges and bumps, and the ride is poor on the optional 19-inch ‘turbine’ wheels. Which you’re going to specify unless you happen to like the poverty-spec BMW 3-series look. The brakes have kept their off-ON, grabby quality and bite with a vengeance.
Yet nothing, absolutely nothing prepares you for the full force of 5.5 litres of bent eight and forced induction. Any gap in traffic is an overtaking opportunity, and any straight a chance to triple the speed limit with ease. And all with the roof down should you so wish. Make no mistake, the SLR rag-top is seriously, addictively fast.

Is the interior befitting a £350,000 roadster?
A moot point. It is if you're small. The engine layout and packaging brings a cramped interior, especially for a car that is supposed to be a GT. And quality isn’t great either: the centre console is a mix of Merc SL bits sprayed with the same silver paint found in the Chrysler Crossfire’s interior. Maybe that’s a bit harsh, but you get the idea.
But as money will not be a problem for those buying this car, you can spend thousands customising the whole interior. But even the biggest chequebook in the world can’t make it any more spacious.
However, all is forgotten when you lower the roof, feel the sun on your head, and hear those exhausts bellow as they exit just fore of your feet. The SLR's trump card has always been its rumbling, baritone V8 soundtrack and it's only amplified in the soft-top.
Anything else I should know about?
The SLR Roadster has a small boot that may struggle to house your average golf bag, despite bulbous rear. And although the gullwing doors are truly stunning, the A-pillars that support them are thick and obstruct visibility badly. And even in this open-top you know you’ll be safe as McLaren’s carbonfibre tub combined with Mercedes safety know-how make this a good car to have a crash in. (Not that you'd want to.) Finally, there are five seat sizes for the driver (who will always sit on the left), and four for the passenger - so if you are a large banker you should make sure your passenger is slim-hipped.

Verdict
A Ferrari 599 is better full stop, a Rolls-Royce is the better convertible and a Zonda more thrilling. But none of them can match the immense acceleration of the SLR Roadster combined with a folding roof and automatic gearbox. Yet the McMerc is also a darty, nervous hypercar that is still not properly resolved.
But just enjoy the power, the noise, the wind in your hair, and the effortless performance. There are better supercars and convertibles out there, but none of them are quite like the SLR, for better or for worse.
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IMHO they should have gone with a carbon fibre manual folding hardtop, with vacuum suction when you bring it a few inches into the windshield header or within a foot of the boot (when closing it). They should also have boosted power to 700+ and called it a day. What they are left with is a compromised car that does not look much more than a fancy SL in terms of desirability, and with a top up, looks like it has a tupee.