Pre-season aerodynamic testing is underway at East Sale in Victoria, with Holden, Nissan and Ford participating ahead of the 2015 V8 Supercars Championship.
While Holden and Nissan are looking to update the respective Commodore VF and Altima, Ford is homologating a new model racer, the FG X Falcon.
The conversion of the 2014 FG II V8 Supercar to FG X specification does not require a redesign of the 'New Generation' chassis introduced in 2013, but new exterior panels and aerodynamic appendages have been developed, and require approval by V8 Supercars.
Driving duties for the FG X are being shared between Mark Winterbottom, David Reynolds and Cameron Waters throughout the testing period, which began on Saturday and concludes on Saturday January 17.
Nick Percat is behind the wheel of a Commodore, Todd Kelly steers the Nissan Altima, and Todd Hazelwood is driving the V8 Supercars New Gen Ford Falcon prototype, the control chassis used in all previous aero testing.
After the 'ruler check' in August 2014, additional testing procedures are being applied.
Teams are allowed up to five personnel managing each car at the test, including each manufacturer's homologation representative - Prodrive Racing (Australia) team manager Chris O'Toole, Nissan Motorsport General Manager, Engineering Craig Spencer and, on behalf of Holden homologation team Walkinshaw Racing, Ludo Lacroix, Triple Eight technical director.
The V8 Supercars technical department is present under the direction of David Stuart.
This year's is the fourth successive pre-season homologation test - each manufacturer will submit desired changes to V8 Supercars and if approved, commence work on the race cars as the sydney.com SuperTest approaches, running from February 7-8.
Once a model is homologated, teams are required to start the season with the homologated model.
While all Holden teams are not technically aligned, they all will be required to adopt the homologated design for the Commodore.
However, in Ford's case, because the FG X poses such a big change, there may be two separate models running until all FG X's are built.
It is expected Prodrive will run at least two FG X's at the Clipsal 500 for Winterbottom and Chaz Mostert, as will DJR Team Penske for Marcos Ambrose.