XPart has recruited 250 UK garages to its AutoService repair franchise in less than three years since it was started.
The milestone was marked with the recent appointment of Leeford Motor Company in central Leeds.
The franchise network was created after the collapse of MG Rover in 2005 to provide Rover owners with access to specialist servicing from factory-trained technicians using genuine OE parts.
Member garages get business management, marketing and technical support, plus access to XPart's £20 million stock of MG Rover parts.
The appointment of Leeford Motor Company makes XPart’s AutoService network one of the largest service and repair franchises in the UK.
Don Lindsay, service marketing manager, XPart, said: "There are still more than 1.3 million MG Rover vehicles in the UK, which creates excellent demand for specialist servicing and genuine parts."
The company recently added a specialist Mini module to its offering, providing garages with the diagnostic tools and service parts needed to service the brand.
"While we have reached a key milestone in the development of the network, we will continue to expand further," said Lindsay.
"We will continue to grow the network and offer our garages programmes which are demanded by motorists and continue to offer good revenue potential."