It is unlikely that the promised electric vehicle subsidy of up to £5,000 per car, which is due to be introduced in 2011, will go ahead if there is a change in government following next year’s general election.

The Conservative shadow transport minister, Theresa Villiers said all the promises - including the £230 million electric vehicle subsidy - announced by the current government earlier this year would be reviewed if the Tories won the election.

“The state of the public finances means that we are facing a desperate situation,” she told Fleet News.

“All the commitments that this government has made will be subjected to value for money review, were we to win the general election.”

The Liberal Democrat shadow transport minister Norman Baker was more definite about his party’s plans for the subsidy should they become part of the next government.

“The idea of having a subsidy for electric vehicles but not having one for vehicles that are very low emitting seems to be the wrong approach,” he said.

“I do not favour a subsidy but I do favour measures that incentivise low carbon vehicles.”

He said the Lib Dems would introduce a showroom tax system that would penalise high-emitting car buyers with a large tax bill. The money from this would then be used to cut the cost of a new low-emitting car.

“I would call this a graduated showroom tax,” said Baker. “Those at the top end would pay - provide a discount - for those buying at the bottom end.

“It is not a subsidy direct from the exchequer it is an internal market subsidy from sales which means that the money from one end goes to the other.”

The Department for Transport is still ploughing ahead with the scheme and is finalising details of how the subsidy would be applied should Labour remain in power.

It is considering just two options – either a direct showroom discount of up to £5,000 or asking lease companies to ‘bid’ for subsidy money to allow them to purchase a number of EVs that they would then lease to companies and private motorists.

Commenting on the news that both opposition parties would be unlikely to follow through with the EV subsidy, a DfT spokesperson said: “We are committed to these measures and will be making decisions shortly.”