DriveCam lets parents keep an eye on bad teenage drivers

He avoided an accident, but not the wrath of his parents.

A digital camera attached to his rear-view mirror sent a signal to a remote computer, which triggered an email to his father.

Later, his parents were able to examine a video recording of the 10 seconds before and after their son had braked.

The spy in the cab, which has long been used to monitor the movements of truck drivers, is arriving in cars driven by American teenagers.

In an attempt to reduce an alarming accident rate among young drivers, an insurance company launched a pilot scheme in three states last week offering free spy camera technology to parents whose children drive.

Preliminary studies have shown sharp reductions in what the insurance company describes as "risky driver events" - swerving, heavy braking, sudden acceleration or collisions - in cars with so-called DriveCams.

Despite complaints from some teenagers that their privacy is being invaded, the DriveCams have been welcomed by nervous parents whose insurance payments rocket whenever a teenager is added to their policies.

Car accidents are the leading cause of death for US teenagers, who are nine times more likely to crash a car than adults.

The DriveCams have one lens facing the driver and a second pointing towards the road. Images are only saved before and after a sudden change in the car's behaviour. Parents can log on to a website where they can review incidents.

The footage from the preliminary studies confirmed that teenagers were more easily distracted than adults but lacked the driving experience to correct mistakes.

"In some videos we've seen kids text-messaging, fiddling with the stereo and talking over their shoulders to their friends while they were driving," said Steve Witmer, of American Family Insurance. He said a pilot scheme for 60 families in Minneapolis had reduced risky driving by 70per cent.

Teenagers worried that the cameras will detect their activities in the back seat should note that the DriveCam does not function when the engine is switched off.