But the remaining few which have yet to register could be subject to fines of up to £5,000, a factor which can now only be accredited to the fleet, says Tony Leigh, chairman of the Association of Car and Fleet Operators (ACFO).
He said: 'I don't believe any fleet has a defence if they haven't acted in accordance with the directive. It is in all our interests to provide the information for both the police to be able to identify uninsured drivers and for easy tracing of vehicle insurers in the event of a hit and run accident.
'Both methods of uploading to the MID, which range from those fleets who manually put in the odd car now and then to those who do overnight electronic updates, seem to work well. There is no excuse for not providing the information,' he added.
The database, which is part of the Fourth EU Motor Insurance Directive, was subject to problems early on. The final legislation appeared only days before the January 20 deadline, fleets failed to contact their insurers early enough and there were problems registering vehicles on the database.
Earlier this year officials at the Motor Insurers' Information Centre (MIIC) said that 50,000 policyholders had done 'nothing at all' to comply with the EU legislation, warning they faced fines totalling £250 million.
However, fleets appear to have overcome the earlier difficulties, according to Stewart Whyte, managing director of Fleet Audits.
He said: 'Apart from little things which can be interpreted as teething problems with large IT projects or operating errors in terms of insurance, there don't appear to be any large scale problems. Despite problems with the Government and insurance companies, the results achieved are a credit to the fleet industry.'
A spokeswoman from the MIIC said the group would be issuing a report on the number of fleets that had registered on the database at the end of May.