Toyota has just built its one millionth hybrid, a milestone that took 10 years to reach, but the second million will come within 18 months. Toyota also expects to be building one million hybrids a year by 2010.

Fewer than 2,000 Toyota hybrids were sold in the UK last year, while worldwide Toyota sold 320,000 out of total sales of 6.6m. The 2007 Prius target for Europe is 31,500.

But the hybrid Prius – now in its second generation and due a revamp and relaunch in Tokyo later this year – has had an impact vastly disproportionate to its sales.

A senior executive for fleet sales in Europe revealed that because of Toyota's refusal to discount to fleets, it was never invited to tender. Now, because of user-driver interest in Prius from fleets, which Toyota is quite unable to satisfy, the door is open to fleet sales opportunity for Toyota’s conventional cars.

Yoshihiro Onomura, the general manager of Hybrid Systems said there was not much technical development of hybrid: "Quality is the number one priority. Most of our engineers are working on quality, not on hybrid technology."

He sees no real virtue in diesel hybrids unlike PSA Peugeot Citroën.

Both technologies are more expensive than petrol engines and both have noise issues that are difficult to resolve. To prove it has been tried before being side-lined for cars, Toyota showed a delivery truck suitable for Japan with diesel hybrid.

Shinzo Kobuki, the managing officer of Toyota, expressed caution about bio fuels and hydrogen.

He said there was a danger of biofuels competing for land with food producers. For that reason, Toyota trialed with wood pulp ethanol which is derived from fast-growing and sustainable trees.

Hydrogen has technical problems, some of which have been resolved. In particular, Toyota claims to have solved the cold start issue.

"We continue to invest in hydrogen. In particular, we are looking for improvements in starting time and fuel-stack durability," said Kobuki.

"But the development of the hydrogen infrastructure will take a very long time."

Toyota does plan to develop a plug-in hybrid, which can be recharged within hours. Although battery range would be no more than 20 miles, there would be another power source as back-up.

Beyond a 20-mile range, the cost and technical challenges of reducing battery size are prohibitive.

GM has just signed battery development contracts with two of the world’s best battery technologists to get better range.