Imagine a Mercedes-Benz B-Class with rear-wheel drive and a 388 hp 5.5 litre V8 shoehorned into it. Unfortunately, you won’t be able to get your hands on one – the B 55 is an one-off example built by trainees at Merc’s Rastatt plant as a means of showing what can be done if you set your mind to it.

The car was built by a team of twelve second-year and third-year trainees specialising in production mechanics and automotive mechatronics, led by foremen Andreas Wurz from the technical vocational training department and Matthias Rieger from the electrics/electronics installation section.

The design evolved on the basis that the spatial concept of the B-Class was to remain unchanged, with minor indications of the conversion work from an exterior point of view, though the interior was to be upgraded in line with the new vehicle class being aspired to. Most importantly, the vehicle would have to be suitable for day-to-day driving.

The donor car came in the form of a B 200 CDI which had been delegated to the training workshop for learning purposes. As the trainees completely disassembled the car, Wurz went in search of a suitable engine and found what he was looking for, a 5.5 litre V8 with 388 hp and 530 NM of torque. This was transplanted into the B-Class together with a seven-speed automatic transmission and the engine control unit.

The V8 power unit fitted amazingly well, and the team was even able to use the original engine mounts. The ECU also proved to be quite a headache, as it had to be reprogrammed only to process signals from the driven rear axle, and there were serious problems with the steering, but a number of modifications cleared that hurdle.

Going with rear-wheel drive meant getting a suitable rear drive axle, and it emerged that the rear axle of an older W 210 series E-Class would be a very good geometrical fit. Wurz and his colleagues designed a subframe, and extensive forming and welding work allowed the bodyshell to receive the new rear axle. The propshaft of the E-Class also fitted into the B-Class with no further modifications, elegantly concealed within the sandwich floor.

The exhaust system was a clever combination of various replacement part items, and took the form of a twin-pipe system emerging at the centre of the rear end. For the brakes, the team also found the right stuff in the replacement parts catalogue, in the form of the C32 AMG’s system.

As for wheels, the B 55 sits on five spoke design 18-inch AMG sports wheels with 235/40 front and 255/35 rear rubbbers – the maximum steering angle at the front axle was limited to suit. The team also replaced the suspension, installing a K&W coilover system.

For the interior, friends from the training workshop at the Sindelfingen plant provided Alcantara linings for the A, B and C-pillars as well as a roof liner in the same, luxurious material. The seats in a leather/Alcantara combination were fitted by Johnson Controls specialists located on-site in Rastatt. The plant’s paint shop provided the finishing touches – the white car has dark-painted radiator louvres and smoked headlamp lenses, offering very little indication of the demon concealed beneath the car’s bonnet.

At 1,620 kg, the weight of the B 55 is only around 180 kg heavier than the original car, and while no measurements have been taken yet, the Rastatt team feels that the car should manage a 0-100 kph sprint time of under six seconds.

Gallery after the jump.

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