According to a report by the RAC, the number of company cars being driven with illegal faults has doubled over the past year.
The motoring body's Duty of Care Inspection for fleet vehicles highlighted that 36% of those checked failed on the condition of their tyres, while 20% had some sort of fault with their lights. These figures are up 15% and 5% respectively since 2010.
A further 37% of company cars failed the inspection for poor fluid levels - up 26% on last year - and although this isn't against the law, it's an essential part of car maintenance and something that should be enforced by fleet managers.
Other issues identified by the inspection included poor vehicle servicing history, external damage and abnormal noises.
Ron Richards, senior partnership manager at RAC, says: "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."