Fleets searching car manufacturer websites will struggle to find out how much CO2 their prospective new vehicle will produce and how much it will cost them to run, says a report published today by the Energy Saving Trust, Friends of the Earth Europe and We Are Futureproof.

In an online trial in the UK (363 participants) only half of the attempts to find the official CO2 value for a particular UK car were successful.

Marian Spain, director of strategy at the Energy Saving Trust, said: "Nowadays most people do initial online research when looking into buying a new car.

"Our research shows that in many cases, finding out the running costs of cars and their impact on the environment from the car manufacturer website is like looking for a needle in a haystack.

"The gulf between the most efficient family car and least efficient family car is two tonnes of carbon dioxide emissions and £1,000 a year - that's worth knowing about.

"At the same time, even manufacturers of low-carbon cars aren't making the efficiency of their vehicles at all clear. I want to see the straightforward fuel economy label next to every car model viewed online so people can make informed choices."