The local authority spent Â£2m on fuel for its fleet between April and December last year, its audit and scrutiny committee has heard.
Reducing the chances of workers making personal use of vehicles is seen as a way of helping to cut the fuel bill.
Councillor Richard Laird said only "a small minority" of staff were involved.
However, Mr Laird, who is the audit committee's chairman, welcomed the council's decision to install tracking devices on all its vehicles.
He told BBC Alba: "There is anecdotal evidence that a handful, or a small minority, of council staff are maybe using their council vehicle for domestic purposes.
"At the moment it is only the heavy fleet that gets tracked and the bulk of the council's fleet is a light fleet."
Tracking is now to be rolled out across the light fleet so that movements of all the council's vehicles can be checked.
All Highland Council vehicles are to be tracked following reports of alleged misuses by staff, including the use of a van for transporting sheep.