Electric car sales were up by a third in August compared with the same month last year, however just 34 of the vehicles were bought 0.06% of the total number of new car registrations.
The British Vehicle Rental and Leasing Association said the cost of buying and owning the vehicles was still too high for them to be considered a viable company car option.
It has calculated that the cost of owning a Nissan Leaf, for example, is 5000 more than an equivalent diesel car over a typical three-year/ 36,000-mile period.
According to figures released by the Society of Motor Manufacturers and Traders today, 812 buyers have taken up the Government's 5000 Plug-In-Car Grant so far this year.
'With the retail car market in the doldrums, it is the fleet market that is responsible for nearly 60% of new registrations,' said BVRLA chief John Lewis. 'Fleet customers don't buy on sentiment - cost is their main criteria.'
He spoke out as a new study commissioned by the Low Carbon Vehicle Partnership (LowCVP) suggested that it will take at least 15 years before the cost of owning an electric vehicle will rival that of petrol and diesel-engined cars.
The report found that the difference in the total annual cost of ownership between conventional and ultra-low-carbon family cars will fall from around 5000 today to between 500 and 750 by 2030.
This is mainly because the cars will become cheaper to buy as batteries fall in price. The report also found that by 2025 tax breaks of up to 2000 per year will put the cost of owning most electric cars on a par with their conventional counterparts.
LowCVP boss Greg Archer said: 'This study indicates that the cost of electric vehicles will fall substantially, and with modest tax and other incentives could be as cheap to own as conventional cars within the next 15-20 years.'
The study also estimated that the cost of owning a conventional family car for four years will rise slowly from around 22,500 in 2010 to 24,000 in 2020, and 25,000 in 2030 as the cost of CO2-reducing technology also delivers fuel-cost savings.