The Motor Trade Association is calling for a clarification of how the law applies when people take their vehicle from a garage after repairs without paying the bill.
It says a growing number are doing so.
The association has been discussing the matter with the police since July and further talks will be held on Wednesday.
It says removing a vehicle without settling the account could be treated as theft, although the police have been reluctant to get involved before now.
But the Automobile Association says there would need to be an element of fairness before any charges were laid.