The business, a division of communications giant BT, runs 58,000 vehicles with an estimated value of £500m, including 16,000 company cars.
BT Fleet Partners is searching for a partner to help it develop future services. As well as the partner potentially providing business for the in-house garage network, which covers 88 locations nationwide, it would also work on helping BT plan other future developments, including vehicle sourcing and disposals.
The move would be able to take advantage of any review of Block Exemption making it easier for garages outside official manufacturer franchised dealer networks to carry out regular servicing on vehicles.
But BT head of fleet Janet Entwistle said the move was not intended to rival nationwide servicing networks such as Halfords and RAC Autocentres.
She added that the intention was not to sell the BT fleet operations, but said that the partnership would review a number of fleet areas, including provision of funding for the company's outright purchase fleet.
Entwistle said: 'Using a partner means we will be better able to continue to meet the needs of current BT customers, in the long term. We have not chosen our partner yet and the possibilities for fleet operations are being kept very general at present.
'We will be looking for a firm with complementary skills and experience, which can demonstrate a commitment to the commercial vehicle market and share BT's passion for providing quality services which really deliver what customers want.
'Our focus would be on LCV and specialist vehicles. We need to be more flexible than we are today and that would include getting more vehicles through our workshops. BT Fleet Partners has an independent national network of garages, which is central to its operations.'
She reassured suppliers, saying it was 'business as usual' for its current operations.