What kind of technology did it use?
The Electric Drive, also known as the B250e, only had a 28kWh (usable) lithium-ion battery, but it was pretty efficient. Mercedes claimed around 142 miles on a single charge (more like 100 miles in the real world), which would take about nine hours on a normal household socket or as little as three hours if you could track down the right kind of public charger.
For longer journeys, the B had a special ‘Range Plus’ button on the dashboard. Designed for occasional use only, it freed-up additional capacity in the battery to liberate around 20 more miles of range. Mercedes cautioned “over-frequent use of this function [could] reduce the lifespan of the battery more quickly”.
In the UK the Range Plus button was part of the optional Energy Assist Pack. At £945 it was well worth having – its other big selling point was an adaptive energy recuperation system that used front-facing radar to vary the amount of regen based on traffic/road conditions. Some modern EVs have this, but many don’t…
The driver could also manually adjust the level of regen using paddles on the steering wheel. The Pack also added privacy glass, a heated windscreen and extra insulation around the doors and windows were to reduce load on the air conditioning.