James Courtney set the pace in first practice for the WD-40 Phillip Island 500, shading a puncture-hit Scott McLaughlin.
Courtney took his Mobil 1 Boost Mobile Commodore to a 1:30.6461s to lead the way, with Shane van Gisbergen third and championship leader Jamie Whincup a quiet 17th.
Fog at Phillip Island delayed the start of Friday’s support action, but the opening Supercars session ran as scheduled, as the skies gradually cleared.
Following a spate of failures at Phillip Island last year, drivers are on the 2016-construction Dunlop tyres this season, and the harder of the two compounds this weekend.
The two Shell V-Power Racing Falcons completed long runs but McLaughlin’s ended just after completing his eighth lap with a right-front tyre delamination.
Team-mate Fabian Coulthard completed 12 laps, pitting just after McLaughlin had limped back to the pits.
Courtney and team-mate Scott Pye spent the bulk of the session at the top, interrupted by a brief spell for Erebus Motorsport’s David Reynolds during the middle phase.
Entering the final third, Pye sat atop the order with a 1:30.0724s, until Courtney lowered the benchmark to 1:30.9365s with 10 minutes remaining.
Courtney improved on his final run on new tyres, turning a 1:30.6461s to go 0.4263 seconds clear of the field.
McLaughlin - back on track after his puncture - and van Gisbergen got to within a tenth of Courtney in the closing stages, the former ultimately finishing 0.0304s shy.
“It’s been great. We rolled out this morning and straight away the thing went up to the top,” Courtney said.
“The platform feels really quite stable, quite consistent in these long, loaded corners.
“With that stability through the corners it gives us drivers a lot better idea of the grip level you’ve got, so then you can use all of it.
“In previous years here the cars have been really quite nervous. I couldn’t be happier at the moment.
“I don’t know what everyone else was doing, but our car feels good.
“We still have areas we need to tune, but it’s a nice feeling to go out each weekend at different tracks with a competitive package.”
Late improvements put Craig Lowndes, Cameron Waters and Nick Percat into fourth, fifth and sixth, demoting Pye to seventh.
Coulthard also found time late to finish eighth, ahead of Reynolds, Garth Tander, top rookie Todd Hazelwood and the best of the Nissans in Rick Kelly.
Asked if his team was trying to find the limits of the tyres, Shell Ford managing director Ryan Story said: “I wouldn’t necessarily go to that extreme.
“We were doing a race run and you want to find out where things are.
“It wasn’t exactly the best set of tyres that we brought with us either.
“We know where that limit is now, by default, and we learnt a little bit there.
“The tyre difference is the biggest change [since last year], but we’ve just seen in that session it’s mega quick.
“It’s cold here today of course, but mega fast running today.”
Mark Winterbottom’s 200th Supercars event started with a trip through the gravel at Turn 2, a locked left-front on the way in sending the Tickford Falcon wide.
Winterbottom managed to avoid the wall, while team-mate Chaz Mostert repeated the act nearing the 15-minute mark.
Having completed seven and eight-lap runs to end the session, Winterbottom and Mostert wound up 16th and 19th.
Between them, Whincup was 1.1044s off the pace set by Courtney in 17th, one place ahead of Anton De Pasquale who ran wide at Lukey Heights in the final minute.
Andre Heimgartner, like Winterbottom and Mostert, ventured off at Turn 2 in the first half of proceedings and was ultimately 21st.
Second practice for the WD-40 Phillip Island 500 starts at 2:35pm on Friday.