Bicester-based Ecocabs2go, the pioneering brainchild of Union Cars owner Chris Whiteley, uses hybrid cars that reduce emissions by up to 50 per cent.

Mr Whiteley, 46, said: "I've been in the business for 12 or 13 years and now, as we are all trying to be more aware of the environment, this idea is really important.

"Eventually, I hope we can revolutionise the business throughout the UK. I would love to see all my cars go hybrid."

Although the Toyota Prius hybrid car as used by the Lord Mayor of Oxford costs about £10,000 more than one of Mr Whiteley's regular taxis, he believes the investment will pay off.

He added: "We are offering a better service, with uniformed drivers, an umbrella service, opening and closing doors.

"People are very keen on it, the feedback has been fantastic, and for them it doesn't cost any more."

With two cars in Bicester and a new branch opening in Buckinghamshire, Mr Whiteley hopes to open franchises all over the country and is eager to attract corporate clients.

The hybrid car operates like a normal vehicle at speeds above 30mph. Below that, it is run by the battery, and when the driver reduces speed or brakes, it also re-uses that energy.

Also when running on the battery alone, the hybrid cars are almost silent and are quick to highlight their credentials as they are painted green Mr Whiteley added: This is a good way for companies to exercise some corporate social responsibility.

"These cars are much more expensive initially, so it shows we are very serious about this."