Company drivers who use rental cars for business journeys have significantly reduced the number of miles they travel.

While this is good news for the environment – one car rental company says this equates to 30,000g less CO2 being emitted by every rental – it is probably down to the massive rise in fuel costs and companies cutting costs.

In the past two years, the average miles driven per rental has decreased by almost 20% according to National Car Rental’s data as average rental mileage dropped from 564 miles in 2005 to 459 miles per rental in 2007.

“We have seen an interesting reduction in the average number of miles driven per rental,” said Tim Bailey, fleet director said.

“This reduction equates to an average of around 30,000 fewer grammes of carbon emissions per rental, which is obviously good news for the environment.

“Clearly, we can only speculate about the causes for this reduction in mileages incurred but it does suggest our customers are not simply thinking about their destination; but planning their journeys, being selective about how far they drive and choosing an appropriate vehicle – indicating a greater consciousness of environmental issues, congestion and fuel consumption.”

However, while the average miles-per-rental has fallen overall, there have been increases in the mileage incurred in larger vehicles, such as estates and people carriers.

Estate mileages have increased by 15.4% and people carriers by 14.6% in the period 2006 to 2007.

“The reduction of miles in small to medium cars coupled with the increase of mileages in larger vehicles suggests people are beginning to ask themselves how they can travel more wisely,” said Mr Bailey.