Professional services giant Deloitte stands accused of double-dealing by angry Honda car dealers, who say it used confidential information gleaned from auditing their franchises to help the Japanese carmaker reduce payments to them following a major restructure to online car sales.

The dealers are suing Honda Australia for damages related to the abrupt termination of their long-term agreements, but are also putting the ethics of auditing firms back under the microscope. The consulting sector is still reeling from the PwC scandal, where its partners used confidential Treasury information to help global technology clients avoid tax obligations.