Sunwin Motor Group has become Britain’s largest Co-op owned car retail business with the acquisition of 15 sales points on seven sites from Ilkeston Co-op Group.

The motors business of United Co-operatives doubled its turnover (£152m in the new AM100, collated before the deal) with the purchase of the dealerships for an undisclosed sum. Ilkeston Co-op has a £167m turnover in the AM100.

Sunwin’s turnover is close to £300m which puts it just outside the latest AM100’s top 25, and moves it well ahead of Priory (No 31, with a £228m turnover). The UK has about 50 independent Co-ops, originally set up as non profit-making enterprises to sell goods to workers. They are now loosely affiliated and have become professionally-run concerns competing against private businesses in their various sectors.

The expansion makes Sunwin a substantial Renault partner, with eight outlets, and it has also grown its interests in Nissan, Fiat and Peugeot. This was one of the major attractions of the deal, according to Peter Marks, chief executive of United Co-operatives.

“This deal puts us firmly in the big league,” he says. “It clearly demonstrates our intention to invest heavily in our main businesses – we announced a £100m war chest at the time of our annual results. We look forward to developing our motor business further over the coming years.”

Ilkeston Co-op Group’s car retailing business has shrunk to a turnover of £40m but it keeps its Lincoln Motor Village which has Citroen, Fiat, Alfa Romeo, Mazda, Hyundai and Seat franchises. This site is now managed by Charles Procter, previously operations director at Ilkeston which also has Citroen and Peugeot dealerships on separate outlets in Grantham.

John Day, former chief executive of Quicks, joined Ilkeston two years ago after borrowings had soared. The company had been was financially stretched by over-ambitious growth plans and rocked by a fraud within the group. Day will leave by the end of July after seeing through the transfer of the dealerships to Sunwin.