ALD Automotive will manage GM's own lease operations, which include Vauxhall Leasing, Saab Contract Hire and Chevrolet Lease, from the end of the month.
Masterlease had managed the operations for the past eight years but cracks in the agreement between the two companies became apparent when Masterlease stopped writing new Saab business in March.
Despite other lease companies renewing their Saab business at the end of June Masterlease kept its Saab order book closed.
Now General Motors UK (GMUK) has moved the contract over to ALD, which will see the country's tenth largest lease company manage the entire GM UK leasing operation.
GMUK said the agreement to end the partnership with Masterlease was mutual and allowed both parties to "pursue differing strategies for future growth".
Masterlease said it wants to concentrate on larger fleet business and GM's offerings didn't fit with that strategy.
Masterlease will continue to operate contracts written prior to 28 August.
“We are committed to offering all business customers and our retailers a highly competitive ‘one-stop-shop’ package with GM UK Leasing," said Maurice Howkins, GMUK fleet sales director.
"For Vauxhall, the successful Insignia and the growing popularity of the Ecoflex models will drive business for Vauxhall Leasing; we can also achieve excellent growth for Saab Contract Hire with the forthcoming new 9-5 and the 9-3 range, including the new EcoPower models; plus of course Chevrolet Lease will benefit with its growing portfolio of products including the new Cruze.”
ALD Automotive is backed by Société Générale, one of the largest banks in Europe.
It is now the second largest vehicle leasing operation in Europe.
Keith Allen, ALD managing director said: “We are very proud to be the new private label leasing partner for General Motors UK.
"This represents a significant growth opportunity for us and we expect GM UK Leasing’s business customers and GM’s retailers to benefit from our comprehensive range of innovative funding and management products, meeting the needs of both the corporate and consumer markets.”
ALD has experience in this market from operating a dealer services division for more than 10 years.
Vauxhall, Saab and Chevrolet retailers should, therefore, benefit from ALD's current IT systems and a dedicated support infrastructure.
Peter Tatlock, managing director, Masterlease, said: “Recent macro economic developments have driven both parties to re-examine their priorities and make some strategic decisions about future growth.
"The business will focus its activities around attracting and serving larger corporate customers where there is greater opportunity to provide a broader portfolio of services and where we can add the greatest value to our customers.
"Whilst we won’t be exiting the SME market, we expect to trade less here, and as such we couldn’t give General Motors UK Ltd the commitment it required for volume in the sector.”