Drivers have been warned by anti-fraud experts about a car insurance scam known as 'flash for cash'. The scam involves criminals flashing their lights at a junction to indicate it is safe for a car to pull out - then crashing into them on purpose.
The scam, thought to be costing insurers millions of pounds each year, sees vulnerable drivers or those driving newer cars targeted.
It is the latest scam development, following the now well-known 'crash for cash' scam whereby drivers slam on their brakes without warning, forcing the driver behind to crash into them.
Detective Inspector Dave Hindmarsh from the Metropolitan Police told the BBC that once someone has fallen victim to the scam, criminal gangs will then put in a false personal injury claim for whiplash - often boosting their claim by including people who were not even in the car at the time of the incident.
The criminals are also charging insurance companies for loss of earnings, as well as adding fake bills for vehicle recovery, repairs, and even replacement car hire.
"The problem is a growing problem," Hindmarsh told the BBC. "Financially it costs insurers £392m a year - that impacts on motorists as it's an extra £50 to £100 on every person's premium so that's a financial cost.
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"[There are] emotional costs [as] if you're involved in a crash you could well lose your confidence, and if your passengers are children they may well become wary of being passengers in cars, and of course you may get injured or killed."
The flash for cash warning initially came from the Asset Protection Unit (APU), an advisory group that liaises with the police as well as the insurance industry to help investigate fraud.
The Highway Code states that motorists should not assume that someone flashing their lights "is a signal inviting you to proceed". Criminals prey on the fact that most drivers do perceive a flash of headlights as an invitation.