Engines are back in focus as work continues in a bid to ensure parity between the Mustang and the Chevrolet Camaro, the latter of which has dominated the season to date.
While the Fords rolled out with a new aerodynamic package in the most recent event of the season, the NTI Townsville 500, where Dick Johnson Racing's Anton De Pasquale achieved just the marque's second win of 2023, that team was back in action just three days later at Queensland Raceway.
Details of that outing have been kept discrete, but it is understood that the purpose of the exercise was to test a car with an 80mm throttle body, noting that that present specification is 87mm.
Speedcafe understands that the Mustangs which are running today at Winton are split, some on the 80mm and some on the 87mm, in order to validate the theory.
That theory is believed to be that the 80mm would help calm down the driveability of the Mustang and hence prolong rear tyre life, with the work said to be a collaboration between Supercars' Motorsport department and Ford technical minds.
Which Mustang is on which throttle body today is not known, but with the two-car Walkinshaw Andretti United and four-car Tickford Racing squads both at Winton today, it would not be surprising if both have at least one car on each.
Thus far, all six of those vehicles have been out for at least one run of the rural Victorian circuit, which is now bathed in sunshine after a chilly start to the morning.
It was at a recent attempt at a Tickford rookie test day that Supercars engine expert Craig Hasted was seen carrying throttle bodies around the Winton pit lane, hinting at possible changes to powerplants.
Then, however, it is thought that only aerodynamics were ultimately worked on at the time, when Cameron Waters cut laps in Fraser's #56 Tradie Mustang.
That preceded a day of aero testing for DJR, the Ford homologation team, before a new package was approved in the days out from the NTI Townsville 500, which was intended to address a loss of downforce when the Mustang pitches under braking.
The jury is out on whether or not the new bodywork was a success, although the aero-dependent Sydney Motorsport Park, which hosts the next event of the season at the end of this month, is tipped to provide a better indication.