The RAC Foundation has described the take-up of ultra low emission vehicles under the Government discount scheme as "less than electrifying".
Introduced at the start of the year, the Plug-in Car Grant programme offers discounts of up to £5,000 for motorists buying cars with carbon emissions of 75g/km or less.
However, official statistics show the take-up of the scheme has weakened instead of picking up over time.
From 465 electric cars bought under the initiative in the first three months of 2011, the figures are down to just 215 for April-June, the foundation pointed out.
The high cost of electric cars may be proving a deterrent for motorists. Even with the maximum discount the vehicles generally cost upwards of £20,000.
The RAC Foundation said: "Low-carbon vehicle take-up has been less than electrifying."
However, the Government is hopeful that once production of electric vehicles is scaled up by car makers, the prices will reduce.
Copyright © Press Association 2011