HR Owen's senior independent director, Ramon Pajares, has resigned from the dealer group's board.
His resignation comes barely a week after long-serving chief executive Nick Lancaster suddenly left the business.
Pajares' resignation is with effect from HR Owen's AGM on May 17.
HR Owen has been in a strategic review since the arrival of its new chairman Jon Walden.
Walden has taken on an executive chairman role while the group searches for a new CEO.
Walden has prior automotive sector experience, including as former managing director of Lex Retail Group and Lex Vehicle Leasing, and as a former director of RAC.