A WAG has suggested the Mercedes-Benz B-class is the answer to a question that wasn't even asked.

How so? Well, the company already has a small, compact hatch in the A-class and those who really need space can move into a C-class or E-class wagon. So why the need to add another letter of the alphabet?

According to the managing director of Mercedes-Benz passenger cars in Australia, Horst von Sanden, the newcomer "fits everywhere".

"We look at the B-class not as a compact MPV but as a sports tourer," he said.

Both the normally aspirated B200 and turbocharged B200T were a "close conceptual relative" of the R-class, as they were both considered "sports tourers", he said.

Interestingly, Mercedes believes B-class rivals are therefore activity vehicles in the mould of the Renault Scenic and Subaru Forester, and if early indications are right, the car will appeal to a broad range of buyers.

Interest in the car at the recent Australian International Motors Show in Sydney was strong enough to generate a claimed 100 orders.

Mr von Sanden is also aware the B-class may steal some sales from A-class, and possibly even the C-class, and he admitted that there would be "some substitution".

While he said many Mercedes buyers would either opt for a sedan or a hatch, there would be little chance of moving from one to the other.

"There are traditional buyers who would never change from a sedan to a hatch," he said. "But there might be some C-class buyers who might change."

Mercedes expects the B-class and B-class turbo to account for 800 sales next year with an even split between the two.

Most buyers, about 90 per cent, are expected to opt for the CVT automatic despite the availability of a five-speed manual in the B200 and six-speed manual in the B200T.

A powerful turbo-diesel will join the line-up around June next year.

Mr von Sanden said the company was in discussions with the German parent about the possible model, and that the choice was between the 80kW/250Nm B180 CDi and 103kW/300Nm B200 CDi.

"We will start with the petrol engines first and see how it goes," he said. "We expect that a growing proportion of new Mercedes cars will be ordered with diesel engines as we are convinced that the trend towards clean, economical and sporty diesels is set to continue."

Like the A-class, the B-class utilises the "sandwich" chassis concept that locates the engine and transmission partly at an angle under the passenger cabin.

As exhibited in the A-class, this is claimed to offer greater front-end crash protection for passengers as well as a roomier interior and flat floor.

Occupants also sit 200mm higher than a conventional hatch, above the impact zone.

The B-class is 4270mm long and has a 2778mm wheelbase. By comparison Holden's Astra wagon is 4515mm long and has a wheelbase of 2703mm, which means the Merc offers comparable interior room with much larger cars.

The key to its versatility is a height-adjustable load floor as well as split-fold and removable rear seats with an optional removable front passenger seat.

Depending on the configuration, load capacity can vary from 544 litres up to 2245 litres with the rear seats and front passenger seat removed, offering a maximum load length of 2.95 metres.

Suspension is via MacPherson struts with wishbones up front with a parabolic rear axle and coil springs at the rear.

Power comes in the form of a normally aspirated 2.0-litre four-cylinder engine that develops 100kW at 5750rpm and 185Nm between 3500rpm and 4000rpm, or a 2.0-litre turbo that develops 142kW at 5000rpm and 280Nm from 1800rpm.

The B200 will reach 100km/h in a claimed 10.1 seconds and has a top speed of 196km/h, while the more powerful B200T takes just 7.6 seconds to reach 100km/h and has a top speed of 225km/h.

The B200 has a combined fuel consumption of 7.4L/100km while the B220T returns 8.2L/100km.

Standard equipment runs to dual front, side and curtain airbags, a multi-function steering wheel, air-conditioning, front seat armrest, electric windows/mirrors, single in-dash CD stereo, trip computer, leather steering wheel/shift lever, 16-inch alloy wheels, anti-lock brakes (with brake assist), electronic stability control with steer control, brushed aluminium interior highlights, full-size spare wheel and rain-sensing windscreen wipers. Metallic paint is a $1100 option.