Motorists bought fewer electric cars under the Plug-in Car Grant scheme launched by the Government in the second quarter of the scheme, compared with the first quarter, according to figures.
The number of low-carbon vehicles purchased under the scheme dropped from 465 in the three months ended March to 215 in the quarter to June.
The RAC Foundation said: "Low-carbon vehicle take-up has been less than electrifying."
The scheme, which came into force in January 2011, offers a discount of up to £5,000 to motorists who buy vehicles with C02 emissions of 75g/km or less.
Although the incentive is aimed at encouraging motorists to use "green" vehicles, the cost of eligible cars, including the discount, was found to be much higher than £20,000. If motorists do opt for an electric car, they will be especially keen to find the best car insurance deal on the market.
However, the Government expects prices to drop as carmakers increase the production of electric vehicles.
© Press Association 2011