The £700m turnover group, at No11 in the AM100, takes control of two Citroen dealerships, in Derby and Burton upon Trent, which are added to its outlets in Nottingham and Leicester.
Bristol Street chief executive John Tustain said: "The combination of four Citroen dealerships in the East Midlands brings with it significant economies of scale, creating efficiencies and consistency of service throughout the enlarged territory. This is bound to reflect positively on our customers."
Jenny Evans, Bristol Street Citroen managing director predicts a turnover of £50m this year for the division.
"As part of a deliberate growth strategy, we have acquired two respected and established dealerships from Mark Pritchard, who is retiring from the business," she said.