##merc_s.jpg --Right##COMPANY directors, finance directors and senior managers who can afford to dip into the luxury league and are expected to take the lead in moving over to diesel power in an effort to reduce running costs have had little choice but to bypass the Mercedes-Benz S-class range and choose a BMW 5-series instead.

Until now, only the European market has been able to choose the 4.0-litre V8 S400 CDI, but technical problems involved with the right-hand-drive conversion have as yet proved too costly. Hence the introduction of the six-cylinder 3.2-litre direct-injection turbodiesel engine from the E-class featuring a variable nozzle turbocharger and common rail technology.

Hand in hand with increased appeal for the S range, the CDI derivative will further boost sales, which are running at record levels with 37,500 units sold in the first six months of this year - more than the total number sold in the first 22 years of Mercedes-Benz sales in the UK.

Joining the already substantial armoury of 2.8 and 3.2-litre V6s, 4.3 and 5.0-litre V8s and 5.8-litre V12 petrol engines, the new CDI unit develops a healthy 197bhp and a mammoth 346lb-ft of torque at only 1,800rpm, making the S320 CDI a flexible and eager performer. Compared with arch-rival BMW, the S320 CDI beats the 530d on power with an extra 4bhp and 44lb-ft of torque. But the roles are reversed on the economy front with the Mercedes-Benz recording a creditable 35.3mpg against the BMW's better 39.8mpg average.

Through the widespread use of aluminium in the S-class's structure, the new luxury Benz is 300kg lighter than its predecessor, plus a sleeker, more aerodynamic body and a number of technical innovations including Active Body Control (ABC) and Electronic Stability Program (ESP) mean the new S-class is now a much more convincing driver's car rather than a chauffeur-driven passenger's dream machine.

The closest petrol equivalent would be the S280 with 201bhp, but with only 199lb-ft of torque at a much higher 3,000-5,000rpm the driving experience is markedly different. With greater low-gear flexibility, the S320 CDI has an effortless power delivery and for a car that weighs nearly two tonnes, acceleration is vivid: the 0-62mph sprint takes just 8.5secs giving the S-class effortless overtaking ability and the top speed at 143mph is just 12mph short of the V8-powered S430. It is refined too. At tickover, pilot injections which pre-heat the combustion chamber ensure engine noise is virtually undetectable.

AIRmatic (Adaptive Intelligent Ride Control), which adapts the hardness of the shock absorbers automatically to the condition of the road surface, load carried and individual driving style, is fitted to all S-class models and provides a magic carpet ride quality at all speeds. Driver comfort is first class, aided by the electric heated front seats with lumbar adjustment, an electrically-adjustable steering column and seat cushions that move independently of the seat base, so providing extra support for long distance, long-legged drivers. For further luxury, active seat ventilation is an option.

Company car drivers with one eye on the 2002 BIK tax changes will be interested to know that at 237g/km, company car tax will be charged on 30% of the S320 CDI's price which works out at £13,017 - a 22% taxpayer faces an annual bill of £2,863 and a 40% taxpayer £5,206. The BMW 530d is cleaner at 227g/km, but at almost £15,000 cheaper, any BIK comparisons would prove meaningless.

Given, then, that the diesel derivative of the S-class has no direct rivals from Jaguar, Lexus, BMW or Audi in the UK, Mercedes-Benz should have an instant smash hit.