The latest era of parity unrest in Supercars didn't actually start with the introduction of the Mustang earlier this year. It can be traced back to the ZB Commodore, which made its debut at the start of the 2018 season.
While still a four-door body shape, perfectly suited to the Car of the Future control chassis, the ZB was the first Commodore racing car that was based on a car manufactured outside of Australia - and was also a hatchback.
Concerns over the availability of genuine Opel Insignia panels from Germany meant Supercars allowed an unprecedented use of composite panels on the new Holden. Composite doors and guards had been commonplace in the series, and the FG-X Falcon was running a composite rear light bucket thanks to a lack of OEM availability. But the ZB's composite roof and tailgate took it to a new level.