If every driver obeyed the 70mph speed limit on motorways and dual carriageways, it is estimated that 2.1 million tonnes of CO2 would be saved every year.
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 like driver education or telematic observation – that every driver observes the speed limit, the savings would be massive.
“However, this fuel saving would only occur at significant costs in enforcing the speed limit,” said transport minister, Jim Fitzpatrick.
“Enforcement of motorway speed limits does save fuel, but enforcement is done primarily for road safety reasons.”