An MP has accused young motorists in North Yorkshire of "ridiculous behaviour" after police revealed many make dangerous or illegal modifications to their cars without informing their young driver car insurance provider.
Besides substantially increasing the chances of a crash, this invalidates their motor insurance policies.
One of the most dangerous 'upgrades' highlighted by Yorkshire police is the practice of fitting tinted windows with a much greater opacity than the law allows.
In order to be road legal, windows on UK cars must let in a minimum 70 percent of light. But officers reported seeing (but not seeing through) tinted windows which let in just three percent.
"They are a danger to themselves, their passengers, other motorists, and pedestrians," said John Grogan, MP for Selby. "I would hope the police would take vigorous action."
Mike Page, spokesman for the young driver car insurance specialists at Hoot, said: "It's seriously naïve to expect your motor insurance company to pay out following an accident if you modify your car without telling them.
"If you really want to upgrade something, you have to factor in a higher car insurance premium as part of the cost, not lie about it and hope for the best.
"And as for illegal modifications: they've been outlawed for a reason, which is your safety. Fitting one is about as sensible as skydiving without a parachute."