Based on RAC's Duty of Care Inspection checks of fleet vehicles in Q1 2011, 36% failed for tyre maintenance and 20% for faulty lights – a more than two-fold and four-fold increase on respective failure rates in 2010.

Over 37% of vehicles checked failed their inspection for under-the-bonnet fluid levels, an increase of 26% on last year, which could lead to further problems through increased wear and tear rates.

Notable failure rates for other inspection criteria were:

Vehicle service history: 48%

External damage: 10%

Abnormal noises: 2.5%

Ron Richards, senior partnership manager at RAC, said: 'It always amazes me that of the thousands of fleet vehicles out on the road daily under the responsibility of particular individuals, those people are not checking their own vehicle on a regular basis and are rendering them illegal on the road.

'It's true that vehicles today are more reliable than they've ever been, but this has had the unfortunate side-effect of people being less attentive to the maintenance duties that come with running a car or van.

'It could also be said that there's a lack of communication in companies between managers responsible for fleet vehicles and their drivers, so the internal checks and balances are insufficient.

'The current economic climate may mean that companies are reluctant to pay for their vehicles to be checked professionally and regularly, but this leaves them exposed to potential Corporate Manslaughter charges if the lack of maintenance on a car or van leads to a death on the road.'