A third of cars could be incorrectly registered in government databases, making it harder to stop vehicle crime, the public spending watchdog has said.
The report said the DVLA records were vital to fighting crime
The National Audit Office (NAO) said recording correct addresses, postcodes and registration numbers was essential as police cameras were being used more.
Its report also accuses the Driving and Vehicle and Licensing Agency (DVLA) of being slow to correct its records.
The DVLA said the NAO had used old data and many mistakes had been corrected.
According to the report, almost 15% of addresses are wrong because drivers often don't inform the agency that they have moved.
The DVLA said improving record accuracy was its top priority.
A spokesman for the agency said the NAO's figures were from a survey carried out in 2003.
"Since then a number of major initiatives have been introduced to improve record accuracy and facilitate automated enforcement," the spokesman said.
He added that police had no difficult in tracing vehicle keepers from DVLA data in over 90% of cases.
The report generally praised the Home Office's record, saying it had reduced car thefts and vehicle break-ins by 30%.
But there was scope for even more success in combating the crimes - which cost Britain about £2.1bn every year.
The auditors said car park security could be improved.
And they said many councils had failed to set up registers of salvage yards, allowing criminals to "steal" the identities of scrapped cars.
NAO chief Sir John Bourn concluded: "Many of the initiatives to tackle vehicle crime that are in place have yet to be fully implemented."
In 2003 and 2004 there were an estimated 241,000 vehicle thefts and 1.3 million vehicle break-ins.