MERCEDES-BENZ is sending a message to buyers of smaller petrol-engined cars that they do not need to pay a premium for the latest-generation turbo-diesels.

Which is why it has pitched its latest B-class diesel entry at the same price point as its petrol-powered 2.0-litre B200 sibling – $44,900 in manual guise.

The B180 CDI is fitted standard with a six-speed manual gearbox, with a CVT automatic an extra $2500.

The arrival of the common-rail turbo-diesel now brings to three the number of B-class models available, including the B200 and B200 Turbo.

Managing director of the Mercedes Car Group in Australia Horst von Sanden said that despite some earlier questioning as to where the B-class would fit, buyers had warmed to the newcomer.

Since the petrol variants were launched last October, customer demand has outstripped supply. In eight months on sale, 646 have been delivered.

Mr von Sanden said the B-class had appealed to buyers wanting more space and versatility but "wanted the size of a compact car".

"With demand outstripping supply, we are currently in negotiations to try and secure more B-classes," he said.

Mr von Sanden said he expected the diesel to make up around 20 per cent of B-class purchases.

The B180 CDI is what Mercedes-Benz calls its first "compact" diesel car. Like the A-class, it features a unique "sandwich" chassis that positions the occupants 200mm higher above more common hatches, affording better lateral impact protection.

The engine and transmission are also partly in front and partly underneath the passenger crash cell for more effective and control crash deformation in a frontal collision.

The B180 CDI is powered by a 2.0-litre common-rail turbo-diesel developing 80kW at 4200rpm and 250Nm between 1600rpm and 2600rpm. The sophisticated diesel technology also means the B180 CDI delivers 79 per cent of maximum available torque from around 1300rpm.

By comparison, the 2.0-litre petrol engine develops 100kW at 5750rpm and 185Nm between 3500rpm and 4000rpm. The turbo-diesel delivers reasonably strong performance with a 0-100km/h time of 11.3 seconds and top speed of 183km/h while achieving fuel consumption of 5.6L/100km combined.

With a 54-litre fuel tank, the diesel has a claimed touring range of more than 960km on one tank.

The diesel engine also meets stringent Euro IV exhaust emission limits without a particulate filter system, thanks to the latest common-rail technology. As well, the B180 has two oxidation catalytic converters that reduce gaseous pollutants by combining them with oxygen.

Specifications and standard equipment are the same as the B200 petrol model. As expected of a Mercedes, the B180 CDI has a full complement of safety gear, including dual front, side and curtain airbags, stability control, acceleration skid control, anti-lock brakes (with brake assist), four-wheel disc brakes, rain-sensing windscreen wipers, heated electric mirrors, a full-size spare wheel and front and rear foglights.

Furthermore, it has 16-inch alloy wheels, air-conditioning, an armrest between the front seats, single in-dash CD stereo, remote central locking, a 60/40-split folding rear seat (with ski-hatch), brushed aluminium trim, leather-clad steering wheel, gearshift and handbrake lever, a multi-function steering wheel, luggage compartment cover, electric windows, trip computer, tyre-pressure loss warning system as well as a height- and reach-adjustable steering wheel.

Metallic paint is an extra $1100.