A review of fleet managers showed 73% of fleets had not thought of switching from petrol or diesel. Those who had tended to focus primarily on liquefied petroleum gas (LPG), which is considered the closest alternative to petrol.
Hybrid petrol/electric cars such as the Honda Insight and the Toyota Prius - to be launched in the UK this autumn - caught the attention of a third of those interested in alternatives. Electric energy and compressed natural gas interested 11% and 10%.
But nearly a third of fleet managers said they were 'likely' or 'quite likely' to use alternative fuels in the next two years, though they did not predict the proportion of the fleet they intended to change.
Forty two per cent of fleet managers said they were 'very unlikely' to opt for alternative fuels, with a further 12% saying it would be 'quite unlikely'.
The report said: "The refuelling infrastructure for these alternative fuels is relatively underdeveloped, leading to resistance from many fleets in adopting alternative fuels."
Diesel cars are forming a smaller proportion of fleets, too. They accounted for 9% of fleets in 1990, with popularity growing to 23% by 1994. Since then its use in fleets has steadily declined, to 14% now.
The report said the number of diesel cars had fallen as the price rose to match petrol. Unclear environmental messages had reduced diesel's popularity. Diesel fares better among higher mileage company car drivers than among retail owners.