The Newcastle Journal reports that Carshock administrators are looking into claims that multiple finance was obtained on single cars.
Auditors, BDO Stoy Hayward, said there were also ‘difficulties surrounding the identification and location of leased vehicles’.
It added that some customers have not had finance settled on part-exchanged vehicles and should seek independent legal advice. The report said: "This review of vehicle ownership has been a painstaking exercise and is yet to be finalised.
"This review has identified a number of issues regarding the ownership of vehicles including multiple financing of vehicles, the apparent disappearance of a significant number of vehicles and difficulties surrounding the identification and location of leased vehicles."
The report estimated Porritt Motor Holdings, which traded as Carshock and operated seven sites across the north of the UK, ceased trading with debts of £4.4m.
Mike Porritt, former managing director of the company said: "I would very much like the administrators to be able to fully identify the vehicle stock that was present at the time the company went into administration and report accurately to the creditors.
"In my view, the administrators are going to find this task extremely difficult because of actions taken by certain finance companies at the time of administration.
"I am now personally being pursued by finance companies with a view to making me bankrupt so personally, financially my position is as difficult as it can be. I don't want people to think I have walked away from this saying `whoop dee do'."