But the diesel bug has spread, and although many manufacturers have come up with high-performance modern diesels for their saloons and estates, marketing chiefs are only just getting the message that these motors can have appeal for keen drivers.

After achieving its best-ever annual sales performance in this country, the German firm is aiming to underscore its leading position in the business motoring sector by launching a reworked 3.0-litre turbodiesel engine in its 3-series saloon and Touring models.

Linked to a new six-speed transmission featuring a special overdrive top ratio, the next-generation unit provides the 330d cars with an 11% boost in power. And as well as developing 5% more torque, it also offers a 3% cut in fuel consumption to allow BMW to claim it is setting fresh class benchmarks in performance and economy.

But the bad news for aficionados is that BMW GB is delaying the UK launch of a 3.0-litre diesel-engined coupe – the first overtly sporting unit of its type to be offered by its Munich parent and serious competition for the recently-launched Mercedes-Benz CLK 270CDi – because the engine meets only Euro III exhaust emission regulations at present.

A spokesman said: 'We could have put the 330Cd on sale from October, when we will introduce the less powerful 320Cd Coupe, but we have decided to wait because there will then be only a short time before the 330d engine is changed to comply with Euro IV standards.

'Our view is that it would not be fair on our customers to launch a new model, and then change the specification just a few months later.'

Readers can be assured the wait will be well worthwhile, however.

After putting the new car through its paces in Spain, we can report that BMW's latest straight-six unit really does elevate diesel driving to an impressive fresh new level. Upgraded to the extent that almost every component is new, the engine and boasting second-generation common rail technology operating at considerably higher pressure, it is also quieter as well as being more efficient – and new electronics software guarantees an instant start-up in temperatures as low as -5 degrees Centigrade.

Discreetly facelifted bodywork gives the new coupe a more aggressive stance, with restyled bumpers, modified air intake scoops and a power dome on the bonnet. BMW's next-generation Convertible will go on sale in April – but it will not come with the option of diesel power as Audi has done with its A4 2.5TDI cabriolet.

Instead, the restyled and sleeker-looking 330Ci will boast a six-speed manual gearbox as standard and with a sequential manual gearbox (SMG) as an option.

Likely to cost between £1,200 and £1,300 and also to be offered on the 325Ci, SMG is an automated manual change system allowing split-second gear shifts via the traditional centre stick or paddles on the steering wheel.

Both the coupe and convertible will be first to share BMW's major innovation – adaptive headlights. Using computers to interpret information from sensors monitoring speed, steering action and even body roll, this system turns the inner pair of headlights to help the driver see around approaching bends.

A significant safety development, it is likely to be an £850 option.

Behind the wheel

Statistics speak for themselves. And 204bhp at 4,000rpm and a 302lb-ft wall of torque available from only 1,500rpm present a pretty strong case for the credentials of BMW's first diesel-powered coupe.

But the sheer superiority of this new powertrain can only be fully appreciated from behind the steering wheel. While its predecessor was no sluggard, the new engine sends the 330Cd rocketing away from the lights in genuine sportster style. Making a pleasant whirring noise without the slightest hint of clatter, it swings the speedometer needle around to 62mph in just 7.2 seconds. Keep on pressing the accelerator and you start to wonder if a well-sorted petrol engine has been fitted by mistake as the car goes on to 150mph all-out in controlled conditions without showing the slightest hint of stress.

From less than 50mph, this driver's delight pulls in top gear like a Boeing jumbo jet on take-off, even though its super-high sixth gear allows 100mph cruising on the autobahn at a mere 2,800rpm. And the brawn comes with such a high degree of refinement that even at this pace, there's only wind noise from around the door mirrors and A-pillars to disturb the peace.

Driving verdict

A dream machine for long distance use, the 330Cd is also docile around town, with so much power that there's little need to make many gear changes. This car is a diesel delight.

Model: BMW 330Cd
Engine (cc): 2,993
Power (bhp/rpm): 204/4,000
Torque (lb-ft/rpm): 302/1,500
Max speed (mph): 150
0-62mph (sec): 7.2
Fuel consumption (mpg): 42.8
CO2 emission (g/km): 177
Transmission: 6-sp man
Service intervals: variable
On sale: Spring 2004