Japanese companies had a better record than European or American ones, Professor Stephen Blythe said.

But the industry had still not grasped the urgency of the problem - despite promoting its green credentials.

A car industry spokesman said the government could do a lot more to encourage the development of alternative fuels such as hydrogen.

"It is not just a question of manufacturers developing the technology. All of the parties involved in future fuel technology must play their part," said Nigel Wannacott, of the Society of Motor Manufacturers and Traders.

Bio-fuel

Mr Wannacott said Japanese manufacturers had led the way on hybrid electric and petrol cars but all major manufacturers were developing hydrogen and bio-fuel engines.

He urged the government to provide incentives and build infrastructure to encourage the take-up of hydrogen, which he said was about 15 to 20 years away.

But Professor Blythe, who is one of the key contributors to the government future transport strategy, claimed it was the manufacturers who were dragging their feet.

"We have had a lot of meetings with car companies, who promote their green credentials - but they say we are not going to do much for the next 20 to 30 years because our customers don't want to pay more.

"Japanese car manufacturers seem to be much more progressive than some of the European or American ones," he said.

Perpetual motion

He was speaking at the launch of a report on the long-term shape of UK transport policy.

The report includes four alternative scenarios of what life might be like in 50 years time to help industry and government plan future transport infrastructure.

The scenarios are:

    * Perpetual motion - Demand for travel remains strong thanks too continued globalisation and growth. Cars have got faster but more green, air travel still popular but expensive.

    * Urban colonies - Environment top priority for government. CCar use expensive and restricted. Public transport widely used but rural areas lose out.

    * Tribal trading - Energy crisis has caused mass unemploymentt. Long distance travel a luxury few can afford. World has shrunk to local communities for most people.

    * Good intentions - Tough government measures restrict carbon emissions. Traffic volumes have fallen but the market has failed to provide new energy sources. 

Asked which of the scenarios would appeal to car manufacturers, Professor Blythe said: "I suspect they would not favour any of them."

He said the way people used their cars would have to change over time to make it a more "efficient" form of transport.

Road pricing schemes, electronic networks to help people plan journeys better or even replacing private car ownership with public cars-on-demand schemes could all play a part, he added.

Mr Wannacott said the car industry backed "smarter use of cars and commercial vehicles", which would free roads from congestion.

But he added: "I can never see a time when our love affair with the car wanes.

"There will always be an element of glamour: you are safe, you are free to go where you choose, you are not restricted to doing things the way somebody else wants you to do them. It is about personal freedom."