Cambria Automobiles, the top 10 AM100 group, has added two new brands to its portfolio following an acquisition.
The company has bought three Triumph outlets and one Mazda dealership from administrators acting for collapsed midlands retailer Autohaus.
The Triumph businesses, which include the world's largest for the brand at Birmingham, move Cambria into motorcycle retailing for the first time.
Chief executive Mark Lavery said he was also pleased to begin a partnership with Mazda at Northampton, having been in talks with the Japanese carmaker for some time, and he aims to add further Mazda dealerships in the future.
Autohaus's dealerships had been "severely underperforming" and went into administration at the start of October, said Lavery, and he expects to turn them around by applying Cambria's business model.
The acquisition has saved around 45 Autohaus staff.