Meanwhile, liquefied petroleum gas and compressed natural gas have seen duty drop by 29% in this year's Budget. Fleets also face being 'locked out' of city centres unless they take action to clean up their emissions.
Alex Bamberg, company director of the Ecological Engine Company, warns: 'This proposed ban has the support of 140 major cities including London, Edinburgh, Bath and Cambridge which have agreed to take part. They could start introducing bans in two or three years.'
Bamberg predicts that LPG will become as popular as petrol and diesel in the next 10 years and fuel companies such as Flogas, Calor Autogas, Shell Gas, BP, British Gas Vehicle Fuels and Jet anticipate that the Budget price changes should create a surge in demand for alternative fuels.