The company says that a large proportion of fleets that operated cars into year four and 80,000 miles are starting to renew their vehicles in 2010 but that some are opting to keep cars well into a fifth year as they face ongoing financial uncertainty.

Neville Briggs, managing director at CFC, said: 'We are seeing a few customers run cars into a fifth year and getting close to, or exceeding, 100,000 miles. For most managers in the fleet industry, this kind of lifecycle is pretty much unchartered territory.

'There are concerns, the biggest of which is maintenance. Vehicles at this stage in their lives are becoming more and more susceptible to major component failure and fleets need to ensure that each vehicle’s servicing is carried out to the letter of manufacturer standards while regular visual checks on all wear parts take place very regularly.

'Modern cars can take this kind of mileage but it is question of ensuring that they are still in good condition and fit for purpose. Clearly, employers have a legal responsibility to ensure that they are fulfilling their duty of care – but they also have a moral obligation to make certain that they are sending employees out in vehicles that are safe.'

However, Mr Briggs pointed out that companies that were under financial pressure to extend vehicle lives could be also under a pressure to minimise maintenance spend.

He explained: “It is an obvious enough point but companies where managers feel that they cannot afford to acquire new vehicles are more likely to be ones where spending the larger sums that are needed to keeper older vehicles on the road is questioned.

'I’d underline that we have not seen any evidence of this among our customer base which, after all, is professional enough to have fleet software in place. However, just by looking at some of the vehicles that you see on the roads and speaking to company car drivers anecdotally, there are clearly some uncared-for older vehicles being used.'