Scientists have estimated that 2.1 million tonnes of CO2 would be saved each year if UK drivers obeyed the speed limit on motorways and dual carriageways.
This amounts to a saving of 0.8 billion litres of road fuel.
According to analysis for the Government’s Climate Change Programme Review, if petrol cost 116p per litre and diesel 129p, the value of the fuel saving would be £1 billion.
With pump prices now above this, the savings for fleets that insist – through initiatives such as driver education – that every driver observes the speed limit would be substantial.
“However, this fuel saving would occur only at significant costs in enforcing the speed limit,” said transport minister, Jim Fitzpatrick.
“Enforcement of motorway speed limits does save fuel, but enforcement is implemented primarily for road safety reasons.”