We could argue all day about whether the new Mercedes SL is a sports car or a comfortable cruiser for the wealthy and middle-aged. It certainly isn't a thinly-disguised racer but it does put virtually all of the German company's formidable armoury of technology at the driver's disposal. There is no more technically advanced car anywhere in the world.

So let's agree to disagree about whether a hefty 1,800 kg car with the name that means 'super-light' has betrayed its origins as a Le Mans winner. You will know if this is the kind of car that would make you feel good - and whether you can afford the £50,000 that the SL500 is expected to cost when it becomes available in Europe in March.

The original 1950s 300SL was a two-seater coupe but most of the SLs that followed were convertibles, supplied with removable hardtops to justify their exalted prices. The new SL is a coupe and a convertible in equal measure - and changes from one to the other simply by operating a switch between the seats.

Of course, the smaller and less expensive Mercedes SLK showed the way with a retractable hardtop. The only snag with the SLK is that when the roof disappears into the trunk there is hardly any room left for luggage - annoying for the carefree weekend away, never mind a touring holiday in the grand manner.

The new SL could not require such a compromise. Its roof is a masterpiece of engineering. It takes just 16 seconds to lift itself up, separate into four pieces, and fold into the trunk. The cleverest part is how the glass rear window flips over to nestle under the roof panel. It means that the retracted roof takes up much less space and leaves enough room for a couple of medium-sized suitcases - or golf bags - underneath. And to make stowing those easier, the whole folded roof assembly lifts up at the touch of a button inside the trunk.

With the roof on, the SL is a cosy coupe. Drop the top and there is the choice of a breezy ride with the windows down or draught-free progress with them up and the mesh windbreak in place. There are only two seats though; unlike some of its predecessors, the new SL does not have kiddy space in the rear.

If you need more room, Mercedes will direct you to the bigger, more expensive, but quite similar-looking CL coupe. The CL500 was the first car to have ABC - active body control - a semi-active suspension system that provides very accurate wheel and body control using electronically-directed hydraulic plungers. The new SL also has ABC. And it has ABS, ASR, and ESP - anti-lock braking, traction control and stability systems - combined for the first time with SBC, Sensotronic electro-hydraulic brake control.

Brake-by-wire may be the next big thing in car technology. Unlike every other car available, when you press the SL's brake pedal you don't pump hydraulic fluid to operate the brakes. Instead, the pedal is an electrical switch and a computer interprets how quickly you want to stop by measuring the speed of movement of the pedal, the attitude of the car, and various other parameters. The pedal, however, is arranged to simulate the feel of a conventional braking system; for the driver it feels normal.

Throughout the history of the SL series, one thing is a constant: every version of the car whose initials stood for sport and light was ever brimming with technology. And so it is even for the new fifth-generation R230 series SL500. The Mercedes-Benz engineers and stylists have done their job exceedingly well, clothing a large car with 1770kg kerb weight to handle nimbly and delightfully while giving it the means to travel all day long for days at a stretch in sheer comfort and pace that many other cars would be found watching.

In the Sensotronic system, brake application remains hydraulic, the computer directing distribution of fluid from a reservoir maintained at constant high pressure. It controls the brake on each wheel separately which means the ideal division of labour between front and rear wheels and, indeed, from one side to the other if the brakes are applied mid-corner. It has other refinements such as anticipating hard braking by detecting a sharp release of the throttle followed immediately by brake application; the pads are moved into light contact with the disks in preparation for an emergency stop, which can thus be 3 per cent shorter than with a conventional braking system. And when it detects rain - prompted by the action of the windshield wipers - it similarly moves the pads to clear the disks of moisture.

As a safety system, Sensotronic is required to include redundancy - just as in fly-by-wire aircraft - and so the SL has a conventional, fully-hydraulic system operating on the front wheels only, available in the case of a fault or electrical power failure.

The throttle is also electronic and intelligent, adapting the pedal response to the driver's style. By comparison, the speed-sensitive power steering is quite conventional but a rack-and-pinion system is new for the SL and one reason why the new model is so much better to drive than its predecessor.
The steering system is lighter than before but most of this good new stuff has added weight. Using aluminium for the fenders, trunk lid, door skins and that massive hood (140cm long) did something to compensate but the new SL500 has still come out 30kg heavier than the old one.

This new car is so laden with fascinating technology that we almost forgot about its engine and performance. To begin with, there is only an SL500 with the 302bhp V8 engine from the CL500 and S500 and its attendant five-speed automatic transmission. These are exemplary in smoothness and performance. Zero-100kmph in 6.3 seconds (a touch quicker than before) and a controlled maximum speed of 250kmph do not tell the whole story.

With the ABC 'sport' mode selected, stiffening and lowering the suspension, this is one of the fastest and safest cars on a winding road. Body roll through corners is negligible; in 'sport' there is 17 per cent less lean than with the 'comfort' setting, which is nearly 50 per cent less than the old SL in a lane change at 60kmph.

Its multifarious control systems help the driver to achieve optimum traction, braking and tire grip. If we have a criticism, it is that this efficiency comes at the expense of excitement. The new SL is a precision tool but not a riot of fun.

The SL's new style and its smooth cabin furnishings are still those of an opulent two-seater that was designed for the boulevards of Beverly Hills. It doesn't seem quite right to use this car for blasting across mountain passes. But just as it combines the qualities of a coupe and a convertible, the new SL is both a luxury cruiser and a fast and accomplished driving machine. It makes the definition of a sports car irrelevant.

Author: Ray Hutton