The second block of Gen3 prototype testing in 2022 commenced at Queensland Raceway on Tuesday.
The Chevrolet Camaro ZL1 and the Ford Mustang GT Gen3 prototypes are being put through their paces at the Ipswich circuit.
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Tuesday's running is being conducted in high temperatures, with a high of 37 degrees expected.
James Courtney and Tim Slade are running the in Mustang, with Shane van Gisbergen and Broc Feeney testing the Camaro.
The running will be centred on the reliability of the cars, with new parts to be tried and tested across the two days.
The 2022-spec blue-walled Dunlop Super Soft tyre compound will also be tested on Tuesday.
Test days are open for public viewing at Queensland Raceway.
The Gen3 cars will make their racing debut in the 2023 Repco Supercars Championship.