The DVLA sold motorists' names and addresses to a parking enforcement company just seven weeks after it admitted dozens of criminal offences.
Observices Parking Solutions, run by Douglas Harris, was fined £29,850 after a court ruled it had been "recklessly unfair" to drivers last year.
DVLA bosses were aware of the conviction but still sold on the personal details, it has been alleged.
The number of names and addresses being sold by the DVLA to parking enforcement companies has more than tripled since 2006 and its income from the sale of personal data has reached a total of £20.8million over the past five years.
It emerged that DVLA has sold 4.85m drivers' names and addresses to parking enforcement firms in the past six years, charging at £2.50 each.
Companies pursuing parking fines can also make individual postal applications to the DVLA.
The agency has been accused of failing to check if the companies' use for the private information was legitimate
Those buying the details have included 12 firms that were subsequently suspended from accessing the register due to wrongdoing or bankruptcy.
A DVLA spokesman said all companies which made electronic requests had to serve a six-month probationary period where their requests were "closely monitored."
The spokesman added: "Landowners have a right to impose legitimate parking rules so we have to strike a balance - allowing fair enforcement but protecting motorists.
'That is why information is only provided under strict controls to parking firms who meet the standards set by an appropriate accredited trade association and are compliant with its code of practice.
Wolverhampton Trading Standards investigated a number of claims that OPC was breaching the code of practice imposed by industry trade body, the British Parking Association (BPA).
In March 2011, Harris and OPC admitted 36 offences at Wolverhampton Magistrates' Court, which said the firm had been "unreasonable, unfair, intransigent, and had deliberately misled motorists."
Harris, as the company's director, admitted "recklessly engaging in unfair commercial practice which contravenes the requirements of professional diligence." This is a criminal offence under The Consumer Protection from Unfair Trading Regulations 2008.
He also pleaded guilty to displaying 15 misleading signs and sending letters from a debt recovery firm without revealing it was owned by OPC itself.
The DVLA suspended OPC from accessing drivers' details electronically, as the BPA carried out an investigation into the firm but just 44 days later, the trade body gave OPC a clean bill of health and the DVLA lifted the suspension.
That allowed OPC to obtain the drivers' details of 1,120 vehicles it claimed to have caught parking illegally during its suspension and then to buy the details of another 6,000 drivers in the past 12 months.
The revelation comes despite the agency's promise to reform its procedures in the wake of a similar scandal seven years ago.
In 2005, it emerged that the DVLA had sold drivers' details to the bosses of a Portsmouth wheel-clamping firm. The company's directors were jailed for blackmail and extorting money from motorists.