The win came on an emotion-charged weekend as Holden drivers vied to win the final Supercars race for the brand.
Immediately the victory drew comparisons to Whincup, the most successful Supercars driver of all time, who stepped down from full-time racing and handed his seat over to Feeney at the end of last season.
Whincup scored his first victory on the streets of Adelaide in 2006, his first year with Triple Eight, after holding off Todd Kelly.
Former Triple Eight boss Roland Dane was the first to draw the comparison on the Fox Sports broadcast after Feeney crossed the line.
“In 2006 Jamie was winning his first race here on the Sunday in a Triple Eight car, and with Todd Kelly chasing him down, a second behind, and kept cool under pressure for the last 30-odd laps,” he said.
“[It was] just so reminiscent of that, and that was the birth of a champion there, and Broc replicated that this afternoon.
“He beat yesterday’s winner – Chaz is a top two or three driver in the championship at the moment, for sure – and he beat him fair and square.”
Whincup later explained that Dane had made a similar comment as the team celebrated the breakthrough win.
"RD said to me straight after the race, 'mate it's exactly the same as you in '06'," said Whincup.
"Young kid, first year in the team, and he got the chocolates in one of the biggest races of the year. It's like history is repeating itself, which is fantastic.
"I couldn't be happier for him. He's a good kid. He comes from a good family, from a good crop. We've given him an opportunity and he grounded it out and good a win in his first year.
"What an awesome story."
Feeney said the comparisons to Whincup, now Triple Eight managing director, were cool, while also talking through the tense battle with Mostert.
"It's pretty cool," he said. "I wanted to get my first win all year. I left it pretty late.
"The car was awesome and everything fell our way, but we had good speed as well. I knew it was coming, it was a matter of time. I just had to put all the pieces together.
"I felt pretty good out front, probably calmer than what I do in the pack. I could just focus on what I had to do and focus on trying to manage the gap behind.
"That last stint I was trying not to get ahead of myself, and focussing on pushing and keeping myself concentrated, Because it's pretty easy to get carried away.
"I told the guys on the radio to keep me nice and calm and focussed."
