Experts on liquefied petroleum gas (LPG) believe that London Mayor Ken Livingstone will only allow a limited number of vehicles to gain a discount and that if there is a wholesale switch to gas, the discount scheme could be scrapped.
Owners of gas-powered vehicles that achieve TransportEnergy band four levels can register for a 100% discount on congestion charging for an annual fee of £10. But Eric Westlake, who works with Vauxhall as a consultant on alternative fuels, admitted that the discount could be short-lived if more people than expected register clean vehicles for travel into the city.
He said: 'There would be a cut off point where Ken Livingstone would decide enough vehicles had been registered and to allow more would defeat the object which is to cut down on congestion. But the vehicles that qualify for the discount will only be the cleanest gas vehicles, so we do not expect a huge rise in numbers in the short term.'
There are 90,000 gas-powered vehicles on UK roads, about 15,000 of which have been supported by the PowerShift programme. By 2005 the number of gas vehicles is expected to rise to 250,000.