London Taxicabs are expected to meet all the current legislation regarding exhaust emissions, and many of these vehicles are now equipped with an exhaust gas recycling system that utilises a new type of magnetic position sensor developed by Novotechnik of Stuttgart, Germany, and available in the UK from Variohm EuroSensor. The Novotechnik RFC4800 unit is used to monitor the position of the diesel-injectors, effectively measuring the fuel demand. The sensor itself is a two-part magnetic unit which offers a resolution of 12 bits and a linearity (accuracy) of 0.3%. The output of the sensor is absolute, so even if the engine is stopped and re-started the sensor will know exactly where it is at all times. They are rugged enough to stand up to the harshest of environments and since they do not rely on any form of moving contact, they offer long service life.