A panel from the Commission for Integrated Transport and the Motorists' Forum, both of which advise the Government on transport, say the technology would cut injuries from road accidents by 29 per cent and reduce carbon emissions.

The system would require detailed digital maps of Britain's roads, containing every speed limit, to be drawn up.

A device in vehicles would use satellite positioning technology to discover the limit in its location and reduce its speed if necessary.

The groups say the devices should be fitted on a voluntary basis and should contain a manual override feature, meaning drivers could break the speed limit if, for example, they were forced to overtake.

Telegraph.co.uk