Administrators Ernst and Young said 342 employees had been made redundant at Tom Vehicle Rental and Caledonian Truck and Van Ltd at eleven locations across Scotland and England.
They are confident they will sell the business and assets of a third subsidiary, Alistair Fleming Limited based in Kilmarnock, East Ayrshire.
That sale will see its 21 employees transferred to the new business.
Ernst and Young have retained 86 members of staff at the group’s head office in Airdrie for up to four weeks to assist with winding down the business.
Colin Dempster, joint administrator, said: “The group has incurred operational difficulties and associated liquidity problems in recent years that reflect low utilisation of their rental vehicles, as a result of a competitive market, and changing customer preferences.
“Despite the best efforts to save the group, it could not continue to operate as a going concern and administrators were appointed.
“It is with regret that 342 people have been made redundant. Our specialist team will work with those affected to help them claim outstanding wages and other payments due from the redundancy payments office.”
Efforts had been made to restructure its operations and when that proved too difficult, the owners marketed it for sale.
However, no suitable interested parties emerged from the sale process and administrators were appointed.
Employees affected by redundancy will be offered appropriate advice and support in making claims for redundancy and notice pay to the redundancy payments scheme.
Mr Dempster added: “The administrators and fleet funders are contacting customers as a matter of urgency to ensure that the necessary arrangements are in place for them to experience as little disruption to service as possible.”