Nine million privately-owned cars are regularly used on work-related business out of a total grey fleet of 14 million vehicles, according to Lex Autolease.

This is despite the significant challenge they pose to business in terms of their impact on the environment, employee safety and, in extreme circumstances, the potential for corporate manslaughter charges.

“It appears many businesses remain oblivious to the cost challenges, environmental impact and safety risks associated with employees using their own vehicles for work purposes,” said Tim Porter.

“Our research reveals there are far more grey fleet drivers on the UK roads than those with company cars. This represents a significant risk management challenge that businesses of all sizes need to address.”

The analysis showed that three-quarters (74%) of fleet managers always check insurance cover on grey fleet vehicles, but more than one in 10 (12%) said they undertook only sporadic checks.

A further 8% admitted they didn’t carry out any insurance checks at all.

This is particularly worrying when the research also suggests that more than two-thirds (70%) of cars in the grey fleet are more than three years old, but only 39% of fleet managers always check the roadworthiness of these vehicles.

John Webb, principal consultant at Lex Autolease, added: “Energy Savings Opportunities Scheme Audits, to be
introduced from 2015, will include grey fleet. This is a clear indication that regulators recognise the environmental impact of older, privately owned cars used for business journeys.

“They remain the single biggest safety risk to most fleets.”