In Scotland S & S Services, in Ayr, won the award, while other winners included Slip End Garage in Luton, Holdcroft Subaru in Newcastle-under-Lyme, and Cross Roads Garage in Shipston on Stour.
The competition - which is held annually within Subaru's network of approved dealers - evaluates the retailer's adherence to the manufacturer's programme standards, the quality of its used car display and the professionalism of service.
Tom Vause, used car manager for Subaru UK, said: Competition throughout the Subaru dealer network was extremely high but S & S Services has proved to be the best of the rest.