That was thanks to contact with Will Brown, van Gisbergen having arrived unsighted at the scene of Brown's crashed car at Turn 4.
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That left Kostecki only needing to make the finish to seal a maiden Supercars title.
There was, however, an interesting scenario late in the race when Feeney closed up on the back of a conservative Kostecki, before passing him into Turn 9.
While the position swap was good for T8's ongoing teams' championship hopes, it did rule out the opportunity for Feeney to sit right behind Kostecki for those closing laps and try and force an error.
Speaking after the title-deciding race, T8 managing director Whincup said there was no genuine consideration to tell Feeney to hold station and try and distract Kostecki.
“That's not what we're about,” he said. “It goes through your mind, to do a bit of a desperate move or something. But that's not what we're about.
“It's not the spirit of what we're about. We played it with a straight bat.”
Whincup said missing out on the drivers' title was a blow for the team, despite it having been a long shot in the first place.
“A little bit hollow,” he said. “We feel defeated, unfortunately. But that's the way it is. If we didn't care, we shouldn't be doing it.
“Congratulations to Brodie and Betty and Barry. They had the best strategy for the year, which was to have the fastest car. They deserve the #1.
“We'll need a bit of luck tomorrow, but we'll put today behind us and concentrate on the teams' championship tomorrow and see if we can at least get that.”
When asked how van Gisbergen felt after the race, Whincup said: “You're a bit numb when it happens. He was just blinded by the car in front and then boom.
“It's a bit of shock at the start and then it will start to sink in tonight and tomorrow that, hey, we haven't won the championship. And that's disappointing. You don't get the raw emotion until later on.”