Thousands of taxis, buses and council vehicles could be fitted with devices that prevent them from exceeding the speed limit.
The technology — known as Intelligent Speed Adaptation (ISA) — is being tested by Transport for London in a trial starting this summer on all roads inside the M25.
Drivers of vehicles with ISA will be able to select an option that prevents them from accelerating over the limit. The vehicle will also automatically slow down if the driver fails to reduce his speed when he passes a sign marking a lower limit.
The device uses satellite tracking and a digital road map to detect the local speed limit.
The technology is likely to be offered for sale next year to private motorists. Those with six or nine penalty points might choose to have it installed to avoid an automatic six-month driving ban for receiving 12 points within three years.
Transport for London (TfL), which will today announce a six-month trial of ISA, estimates that, if two thirds of London drivers used the devices, the number of road casualties in the capital could be reduced by 10 per cent.
The improvement in road safety could reduce congestion, a quarter of which is caused by collisions. Vehicles obeying the limit would also consume less fuel and be less polluting.
Andrew Howard, head of road safety at the AA, said: “Drivers are divided in their views of intelligent speed adaptation. Some hate it, some want it. Many have questions that will be answered only by trials like those being carried out by TfL.”
TfL said that it had no plans to insist on the device being fitted to any vehicle and hoped that drivers would agree to do so voluntarily.