Click here to read the full BBC story.
Under the taxi's familiar exterior - within its generous 2.6 tonne bulk - the truly special bits are hidden.
The back wheels of the taxi are powered by two electric motors - though it is not an electric car in the conventional sense of the term.
Fuel cells deliver electricity, similar to the way a battery does. The taxi does have a lithium polymer battery that delivers electricity to the electric motors, but this is not its main source of power.
The cab also has a stack of fuel cells that convert energy from hydrogen, which is stored in a tank under the car's bonnet, into electricity.
The electric motors can be powered by either the fuel cell system, or by the battery, or by a combination of the two.
During braking the battery, which is located in the middle of the taxi under the floor of the cabin, is recharged by two sources:
- surplus electricity created by the fuel cells is sent to the battery
- kinetic energy captured during braking is sent to the battery from the back wheels, via the electric motor
With two different power sources - fuel cell system and battery - the taxi could be described as a hybrid vehicle, but again, not in the conventional sense of the term, which usually refers to petrol-electric hybrids.
Click here to read the full BBC story.
Story adapted from www.bbc.co.uk
