The new A-class’ big brother has hit the Nurburgring for shakedown tests, as Mercedes-Benz prepares for the five-door hatch’s launch in January. This car is more than just a long-wheelbase version of the A-class, as its standalone model name – B-class – suggests.

Mercedes originally conceived the B-class as a compact 4x4. However, the concept evolved into this rear-drive ‘Compact Sports Tourer’, a shrunken version of the forthcoming R-class MPV.

Some rugged design cues remain to spell out the differences from A to B: a higher bonnet line and bigger, pentagonal grille, while the disguised headlamp graphics more resemble an edgy update of today’s S-class lights than the slitty A-class’s. Common cues include flared wheelarches and Merc’s new trademark slash along the body.

Under the skin, the B-class adopts a stretched version of the A-class’s overhauled, stiffer sandwich platform, with tilted engine position to channel the lump under the floor in a crash, not into the cabin.

A new rear axle is claimed to boost grip and improve ride quality over the LWB A-class, assisted by adaptive damping which majors on comfort or sportiness depending on the driving conditions. Bigger brakes, speed-sensitive electric power steering, new-generation ESP and up to eight airbags also figure.

Due to be launched in the UK in mid-2005, prices will start at around £15,500. Inside, the B-class promises more rear space than a C-class. High quality materials reflect Merc’s refocus on quality; gadgets include DVD navigation and wheel-mounted controls.

The revised four-cylinder engines yield more power but better economy. The line-up comprises 116bhp 1.7-litre, 136bhp 2.0-litre and 193bhp 2.0-litre turbo petrols, plus 109bhp and 140bhp 2.0-litre diesels. These are mated to five or six-speed manuals, or Merc’s first-ever CVT gearbox, dubbed Autotronic.

ENGINES
The A-class 1.7- and 2.0-litre petrols and 109bhp and 140bhp diesels will be offered, but base 95bhp 1.5 petrol and 82bhp CDI units won’t

DESIGN
Higher bonnet line, more aggressive grille and new headlamps differentiate B-class, but big wheel-arches and body accent line shared with A-class

PLATFORM
Extensively updated version of the Mk I A-class platform, with longer wheelbase, new rear axle design and adaptive damping