The team rolled out the Hangcha- and Schaeffler-backed cars of Ben Bargwanna and Jordan Cox respectively prior to the Sydney Motorsport Park round.
Now, the team has a full fleet of the P51-spec hatchbacks, with a pair of Valvoline-backed machines for Ryan Casha and Aaron Cameron.
The team gave the cars a shakedown at Winton Motor Raceway on Wednesday before being stickered at the circuit on Thursday.
As the designated homologation team, Garry Rogers Motorsport is fielding interest from overseas and more cars are expected to be built.
TCR South America team PMO Racing has reportedly signalled its intention to acquire at least one car.
GRM team owner Barry Rogers said the chance to run the first-generation 308 and the new 308 side-by-side at Sydney Motorsport Park gave the team a chance to benchmark the cars.
“We were just able to see where the strengths and weaknesses are,” said Rogers.
“Obviously with the new car we’re carrying a fair bit of weight.
“It’s quite a bit heavier than the old car at the moment and ride height I think we’re 25 or 30mm higher than the old car at the moment.
“As BoP (Balance of Performance) plays out, hopefully it brings it back into a bit better of a window than where it begins at.
“Really what you aim to do is build a car that’s competitive when it hasn’t got everything going in its favour with regards to ride height, weight and power.
“You don’t want a car that’s only good when everything is in its favour and that’s a bit like the previous-gen car.
“It’s a great little car, but it really needed everything going in its favour to be competitive, whereas you look at the Hondas and the Hyundais, they’re still very competitive when they have been penalised with the BoP.”