An environmental group has warned that electric cars could increase carbon emissions in the atmosphere.
The Environmental Transport Association has called for the new generation of vehicles to carry meters to calculate how much electricity they are using.
The Government has assigned a total of 250 million dollars to promote electric cars, much of which will be used to reduce the cost to the consumer by up to 5,000 dollars.ut the ETA - which describes itself as a "Green AA" - has raised objections about their possible benefits.
"Significant changes to the way we produce and tax power are needed before we will reap any benefits," the Telegraph quoted Andrew Davis, the Association's director as saying.
Electric cars will normally be plugged into the mains overnight to recharge the battery, although some models will also use a petrol engine to top up power during the day.
According to the report, the source of the electricity must also be taken into account when calculating the environmental benefit.
If there is a surge in popularity for the cars, demand for electricity from the national grid will increase.
"Even if the grid has the capacity and the basic infrastructure to meet the needs of electric cars, the new demand patterns they will create may mean greater use of coal and nuclear power," argues the report.
While coal-fired power stations are being considered as one of the biggest sources of carbon emissions, the report says that even if a car uses electricity rather than petrol, it must be fuel efficient for genuine environmental benefit.
A spokesman for the Department for Transport defended the Government's policy.
"Electric and other ultra-low emission cars offer the potential to dramatically reduce the carbon emissions from road transport over the long term. But they are not the only way to reduce car CO2 emissions," he said.