An expected surge in electric car sales did not materialise after government ministers believed "wildly optimistic" figures from manufacturers, a top Whitehall official has claimed.
Writing for the Civil Service Quarterly Blog, Richard Bruce, head of the Office for Low Emission Vehicles, says early budgets and projections were based on "miscalculations" from car companies on the number of green vehicles they expected to sell.
Based on these figures, a £400 million package was launched to encourage take-up of electric cars - including £5,000 grants for drivers buying the vehicles. This funding pot has subsequently been reduced to £230 million in light of the lower level of demand.
In the blog, Mr Bruce said media hostility and consumer anxiety also proved stumbling blocks, despite battery life improvements and the roll-out of over 6,000 charging points across the UK.
Nevertheless he said things are turning a corner and the shift to greener vehicles is "inevitable."
Professor Stephen Glaister, director of the RAC Foundation, said: "Only one thing will lead to a mass market for the greenest cars: a competitive price. At the right price anything can be sold. But most consumers calculate that even with the subsidies on offer these vehicles do not currently make economic sense.
"This is not the fault of the media. Ultimately what is needed is a big leap in battery technology, to increase range and reduce manufacturing costs. That is not yet in sight."
Copyright Press Association 2014