Two-thirds of privately owned cars used for business are unroadworthy, according to the Total Motion vehicle monitor survey.

The research, which looked at over 5,000 company and privately owned vehicles that were regularly used for business, found that 60% of private vehicles were not properly maintained and around a third of drivers were not correctly insured.

Many of these vehicles included cars that had been bought for the employee by a company but which were now owned by the member of staff rather than the business. In contrast, just 0.2% of the company-owned vehicles were not suitable to be on the road.

"It is clear that the safety issues raised by private cars being used for business are not being addressed," says Simon Hill, managing director of Total Motion. "Even where companies are introducing duty-of-care policies they are failing to enforce them."

But Hill believes that garages must also share some of the blame for encouraging drivers to spend their full cash-for-car allowances on leasing prestige brands, such as Audi, BMW and Mercedes, on a non-maintained basis, meaning that many drivers have to pay for their own maintenance when vehicles get older.

"If ‘inessential' service and repair costs are not covered by the allowance, our evidence shows that cars are neglected, especially when high interest rates are already reducing the driver's disposable income," he says. "We estimate that around a third of drivers surveyed were in this position."

The majority of the maintenance problems identified with the vehicles were tyre-related and should have been picked up by any driver making basic safety checks.

But 91% admitted they had failed to perform such checks and 98% said their company did not follow up on whether they had been carried out.