All is not well at Mercedes-Benz. Quality issues have dented global sales, and Germany's premium car maker is having to look seriously at its product range. I've often described Mercedes as the purveyor of some of the best cars in the world. Now I'm not so sure. There is still much for Stuttgarters to be proud of - but there is a gnawing reliability problem with some of their cars, and indifferent quality on others.
The SL has largely escaped criticism. This supercar icon has a rich past. Created as a link to the company's legendary racing years and the fabulous gullwing 300 SL, it is regarded as a supreme example of the automotive engineer's art.
The iconic R129 SL was the fifth generation of the mighty roadster and slipped into history in 2001 after 12 years of production. Around 200,000 were built, and its departure was a body blow to its fans.
Its R230 replacement, unveiled at the 2001 Frankfurt Motor Show, was hailed as a quantum leap ahead, and in many ways it is. In roadster terms it represents the best in luxury, power and design in the "grand touring" tradition - but look closely and it's easy to see how Mercedes has built a replacement for the Amazonian-handsome R129 while saving money.
I was horrified to find my £60,630 SL 350 test car had a flimsy plastic grille in place of the R129's crafted fluted metal; bemused to understand why the stainless steel kick plates of the predecessor had given way to tacky plastic trim and "silverised" aluminium; sickened by the lucky-bag look of the wood trim and disappointed to find cheap plastics used for the dramatically styled and comfortable cabin.
The full-size steel spare of the old R129 has gone too - replaced by a deflated space-saver which needs the electric pump cradled in its centre to blow it up before it can be used. These savings have had another effect - the new SL, despite more power and a better ride, is significantly lighter than the R129's battleship construction. While the old entry-level SL 280 tipped the scales at 1.81 tonnes, the kerb weight of the smallest-engined SL, the 3.7-litre 350, is only 1.75 tonnes including its graceful power-folding metal roof.
The sleek new model is 1½" longer than before, ¼" taller and 2½" wider between the door mirrors. The SL 350 offers more headroom than the old car but, curiously, the cabin is not as wide. There was an inch more to play with in the R129. And where the previous model offered at least some restricted space for two small passengers behind the front seats, the new SL is designed strictly for two.
But it's not all bad news. The SL is still the graceful queen of the luxury grand tourers. It drives beautifully and can devour mile after mile of sinuous Highland single-track with the disinterested ability of Michael Schumacher on an afternoon drive in the country. It may be more brash than its predecessor, but it towers above the competition in its ability to cover distance.
The SL 350's ride quality has been criticised as inferior to the heavier SL 500. I don't agree. The combination of body weight, wide 17" alloys, excellent springing and damping suits the 350 perfectly. The new rack and pinion power steering is speed-sensitive and beautifully balanced. Whether you are manoeuvring the monster in tight city traffic or winding it through the mountains of Torridon, the car communicates incredible feedback and feel for its size.
It was easy to forget the SL's bulk. Passing traffic in Applecross sensibly pulled well over to give the Teutonic two-seater as much room as possible when I softly growled through the misty Pass of the Cattle. High average speeds are easy with the SL 350, and despite brisk hill climbs from sea level and cresting summits more than 2000 feet above Loch Carron my fuel consumption remained around 23mpg over 500 glorious miles.
The ultimate SL experience is to fold away the metal vario-roof. In just 16 seconds you can trade air-conditioned snugness for the joys of open-top motoring. I traversed the West Highlands on a bracing autumn day, roof down. Mad? Not quite. With the neat one-piece wind deflector strapped to the roll-over bar - a task which takes just seconds - and the four side windows rolled up, the SL's cabin remains draft-free and calm to the legal limit and above. Noise levels are low, and the climate system and heated seats so efficient that comfort is never an issue.
The SL 350 is a classic incarnation of the grand tourer. It offers space, grace and pace, with enough capacity behind the front seats and under the stowed roof panel for plenty of luggage. Powerful disc brakes with ABS and brake assist meant that, even descending a demanding mountain road in torrential rain, the SL's stopping power was impressive.
Mercedes has also managed to retain the characteristic "limousine" ride with body and suspension control which makes this large roadster a dream on any road. It's a sheer joy to drive, exceptionally strong and safe. Give it a motorway or a Highland single-tracker and the miles simply melt away.
This car is deceptively quick. I've grown used to an older R129 SL 280 with 204bhp, and was initially surprised to find the SL 350 felt it was short-changing me with a reputed 245bhp. But I was deceived. The acceleration times and pulling power were substantially better than on the old model. It's just that the 350 feels so relaxed and able it's easy to assume your progress is more laid-back.
From rest to 62mph takes an effortless 7.2 seconds compared with the old SL 280's 9.8. Top speed is a limited 155mph compared with 141. Overtaking power is instantaneous with silky-smooth down changes on the surprisingly good standard equipment Sequentronic six-speed manual with its clever automatic selection system.
The SL 350's lack of drama is down to torque. A mighty 258lb/ft from 3000rpm against the SL 280's 199lb/ft makes all the difference, and turns the 3.7-litre 24-valve V6 into a rewarding performance car.
I found the cost-cutting measures on trim hard to swallow, but the R230 SL is still Europe's two-seat top-drawer class act.
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