Fleets have to wait nearly three days before getting back on the road, forcing them to incur the substantial costs of providing a replacement vehicle to essential car users.
Because hi-tech vehicle security systems are so safe, drivers who have lost their keys or experience immobiliser problems can only watch as their vehicles are towed away to be fixed at a garage.
A survey of 400 AA members who had experienced a key or immobiliser breakdown found 88 per cent of drivers had to have their cars towed away. Only 1 per cent could be fixed at the roadside. On average, drivers were left stranded without their cars for between two and three days.
Chris Patience, AA head of technical policy, said that fleet decision-makers must warn their drivers on the consequences of losing their keys.
'If a car comes with more than two keys the fleet department should hold a spare so if a driver does lose his keys then there is the opportunity to take a key out to him,' he said.
The report found that 83 per cent of drivers supported the AA having access to sensitive security related information in order to help drivers fix their cars.
There was also a strong indication of the need for security among fleet drivers with 62 per cent saying they would look more closely at security measures for their next car and 59 per cent of drivers saying that despite the problems, security systems were worth the hassle.