The Driver and Vehicle Licensing Agency (DVLA) is on course to make £10 million this year by selling drivers' details to parking companies.
Research conducted by the RAC Foundation found that more than four million vehicle records will be released to parking companies over the course of 2016-17 financial year, 15 times more than a decade ago.
The money comes from the fact that companies can apply to the DVLA for car owners' addresses to pursue parking penalties. The agency charges £2.50 each time, with The Times reporting that privately owned parking firms often charging penalties in excess of £100.
The rise in requests soared after the government banned parking firms from clamping vehicles on private land, with some companies being accused of sending threatening letters to motorists who owe them money. Evidence has even shown timestamps have been altered on photographs to falsify tickets, leading to some companies being banned from accessing the DVLA database.
Steve Gooding, director of the RAC Foundation, said: "In an ideal system, few if any drivers would get penalty charges, certainly not several million annually. Yet we have heard of examples where some firms actually pay landowners for the privilege of managing their car parks in the anticipation that they will make their money back from penalties. How can that be right?"