The new 4.3 acre plot in Chester includes a state-of-the-art service centre with 26 service bays and a body shop.
The independent car retailer claims the new site increases the service capacity by more than 250% and has led to a 10% increase in staffing.
The expansion came after the group secured £7.6m backing from the Co-operative Bank. The loan was also used to extend and improve its dealerships in Southport and Warrington.
Quoted in the Liverpool Daily Post, Halliwell Jones Group finance director Glyn Howes, said: ‘We are very grateful for the support of The Co-operative Bank, who have backed our business strategy.
‘This is an exciting time for the group, in particular with the expansion at Chester.
‘Success can bring certain challenges and the new development at Chester allows us to deliver the excellent quality of customer service that we aim for. We are now operating more efficiently, but also creating more jobs. We now employ over 350 staff, with turnover expected to break the £240 million barrier in 2013.’
The Warrington based car group, which also holds the naming rights to the 15,000-seater Warrington Wolves rugby stadium, has five sites around the North West and North Wales.