The new breed of Supercars features a slashed downforce figure relative to the Gen2 vehicles, by over 60 percent, which should dramatically affect their behaviour.
For Heimgartner, who topped both sessions this week at Sydney Motorsport Park, the difference is not so apparent on short runs.
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“It's pretty interesting,” said the New Zealander of his experience in the R&J Batteries Chevrolet Camaro.
“It's obviously very different as we all know, with the aero and stuff, but I think over one lap they're actually not completely different.
“There are some slight differences as far as how the car moves around a lot more on the tyre but I think where we'll see the biggest difference is once you get past one or two laps; this car uses a tyre lot harder.
“It's actually quite interesting especially here at SMP when the degradation is quite high, so it's going to be good racing and it's anyone's guess how Newcastle will go.”
Heimgartner was well over a second faster than anyone in the morning session at Eastern Creek, when he ran a set of new super soft tyres.
His team boss, Brad Jones, reasoned that it is “hard to read” too much into the timesheets given discrepancies such as tyres and also weight, with the regulated minimum as yet unconfirmed.
Heimgartner was certainly confident on his way to the all-in test after two days of running at Winton in the preceding week, but was wary of rivals' potential “games” in Sydney.
“I think we looked after the tyres at the test day so we had more of a systems check and then [at SMP] had more saved up,” explained the 27-year-old.
“So, for sure, we chucked some good tyres at it and it was as the timesheets say – we ended up at the top, which is good – but you don't really know a hundred percent until you get to the round.
“Obviously, people play games, they don't show their hand as it always is, so we'll see when we get to Newcastle.”
The Thrifty Newcastle 500 takes place on March 10-12 although, before then, Supercars will conduct further aerodynamic evaluations while other teams are set to undertake private testing at either Queensland raceway or Winton.