Kostecki quickest in Newcastle 500 Supercars practice

Gen3 is underway in Supercars and the new makes have delivered ultimate balance across three practice sessions where Brodie Kostecki clocked the fastest time ahead of Saturday's qualifying and first 250km race.

Plenty of anticipation surrounded the new Gen3 Ford Mustangs and Chevrolet Camaro's as they finally graced the streets of Newcastle on Friday.

And they delivered parity across the day.

Five Mustang's and five Camaro's made up the top ten in all three practice sessions; Kostecki's new Coca-Cola entry the quickest in the final stages of P3.

Kostecki pipped reigning champion Shane van Gisbergen by six one hundredths of a second as 15 drivers finished with a final time under one minute 12 seconds.

Earlier in the day, only five made that feat in practice two, and Andre Heimgartner the sole runner in practice one.

As the day's action came to a close, Tim Slade was poised to lead all drivers on the eve of his 400th career start before Kostecki, van Gisbergen and Chaz Mostert came roaring home on fresh tyres to top-out the grid.

Slade finished fourth ahead of Saturday's early qualifying, with James Golding fifth.

Mostert, this year in a Ford Mustang, was one of a number of drivers who said Friday's sessions were all about important data to better understand their cars.

"Today was just like test day four for us," Mostert told reporters.

"It's good to get the first day under the belt. I'm sure we'll go through some data tonight, talk about some technique stuff, how we can make the car better but everyone's got the same type of thing.

"It's exciting when you've got a new car and a new beast to get your head around - it definitely doesn't drive like the old ones."

Mostert, along with van Gisbergen and Heimgartner arguably delivered the most consistent performances on what was a challenging day for teams.

Heimgartner showed serious pace to end a tentative practice one by all drivers the fastest, before van Gisbergen improved on his compatriot's time by two tenths of a second later in the day to lead the second session.

All drivers showed activity in their narrower cockpits and dealt with curb compliance issues in their new Gen3 models.

The braking area of turn two was an issue early on with several cars going down the run-off.

Not only are drivers managing rebuilt set-ups, but they are also adjusting to Newcastle's narrow streets in their first action around the circuit since 2019.

The field quickened over each session with the gap between all 25 drivers shrinking as the day transpired.

Saturday's qualifying begins at 10.15am AEDT with a top-10 shootout to follow at 11.35am AEDT.

Race one of the Supercars season then follows at 2.20pm AEDT.