Aerodynamic changes to the Mustangs were finally ratified by Supercars on Wednesday night following tense negotiations involving both the Ford and GM homologation teams.

The aero tweaks consist of a removal of the leading-edge packer from the side skirt, adjustment to the rear wing position and angle range, and smaller, US-specification side mirrors.

The rear wing has been moved 25mm up and 25mm back, with a slight reduction of its maximum angle of attack.

All three elements of the package were part of that run on the Mustangs in the final two events of 2023, before the end-of-season wind tunnel testing resulted in changes to both cars.

While essentially reverting to the older spec has raised question about the value of the wind tunnel, it has allowed Ford teams to reuse parts they already had in stock.

Dick Johnson Racing, Tickford Racing and the Blanchard Racing Team all arrived at The Bend with their Mustangs in the revised specification.

Grove Racing and Walkinshaw Andretti United are changing the parts at the circuit, the latter relying on DJR for at least one more side skirt to complete their cars.

The differences detailed in the images included in this story are aimed at reducing the drag of the Mustang package that has been run across 2024 and the 2025 season to date.

That’s also believed to come with a reduction in downforce – a trade-off Ford has been willing to make to close a straightline speed deficit identified in Supercars’ latest parity analysis.

The straightline performance of the Mustangs relative to the Camaros will also be aided by the re-introduction of a 30ms shiftcut offset between the marques.

Shiftcut offsets were used by Supercars throughout the 2023 season as a band-aid parity fix before wind tunnel and AVL dyno testing took place.

How much of an impact the latest changes will have this weekend at The Bend is unclear.

Ford teams will have five practice sessions to tune around their aerodynamic balance shift before qualifying, which will be followed by a Top 10 Shootout and a 500km race.

DJR and Tickford already ran the parts during the pre-Enduro Cup test at Queensland Raceway, while Groves also sampled them during Kai Allen’s subsequent rookie test at The Bend.