The impending debut of the new Ford and GM Supercars has been complicated by a debate over parity that has been raging since aerodynamic testing last November.
The aero homologation process, known as Vehicle Control Aerodynamic Testing, left Ford dissatisfied with the aero balance between the two models, and led to a campaign from the Blue Oval for changes to be made.
That led to a re-run of the VCAT process at Temora Aerodrome last week, run by Mark Skaife and David Swenson, from which sources quickly indicated that genuine progress had been made.
While Supercars is yet to make any formal comment regarding the outcome of the latest VCAT, it's now widely known that changes are being made to one of the cars on the eve of the season.
However it's not the Mustang that will undergo tweaks, with changes to the Camaro currently being implemented by the GM teams.
Ford's concerns are thought to have centred on balance, rather than outright downforce number, with the Ford not having enough rear.
While Ford's initial campaign was to have the Mustang's rear wing altered, Supercars has instead decided to achieve improved balance by tweaking the front end of the Camaro.
The change is an addition to a leading edge of the front bar, which curves upwards to the wheel arch, which is designed to push the aero balance further to the front of the car.
Sources are claiming that the overall downforce numbers won't change, despite there being no changes to the rear of the Camaro.
As for the reasoning behind targeting the Camaro, it's understood that more minimal changes were preferred this close to the opening round of the season.
By changing the Camaro, material can be mounted to the existing Camaro front bar with adhesive, rather than a more extensive rear wing re-design on the Mustang.
Another bone of contention from Ford and its teams has been the performance of the 5.4-litre V8 engine compared to the 5.7-litre Chevy unit.
It appears there is no clear resolution to that heading into Newcastle this weekend.
Instead it's feasible that there will be ongoing tweaks to mapping and shift cuts should a genuine disparity emerge in the heat of battle.
Practice for the Newcastle 500 kicks off at 11:15am local time on Friday.
