This is an interesting idea, its a computer that could make it impossible for drivers to exceed the speed limit. It works by pinpointing the vehicles location by satellite and accessing a database detailing the roads speeds limit to determine how fast the vehicle should be travelling. The device then limits the cars speed to prevent it going any faster than the speed limit. If the vehicle should leave a 40pmh zone and drive into a 30mph zone the device is able to compensate for this and will gradually slow the car down until it is within the speed limit. The device will be trialled in the summer by TFL when a fleet of cars, buses and black cabs will be fitted with it. TFL believe that it could potentially cut accidents by around 10 per cent. It will be interesting to see how the trial goes.