The pair first worked alongside one another in 2015 at Tickford Racing (then known as Prodrive Racing Australia) under the Super Black Racing banner.
The duo were reunited in 2018 when Heimgartner joined the then-factory Nissan team in place of team co-owner Todd Kelly.
Ever since, Talabani has been at Heimgartner's side, witnessing his first solo podium, pole position, and race win in the Repco Supercars Championship.
Next year, Heimgartner will depart Kelly Grove Racing to join Brad Jones Racing and begin a new chapter in his career.
“Absolutely it's sad,” Talabani told Speedcafe.com.
“He was a friend before he came to Kelly Racing from our time at Tickford. That bond and that relationship has just gotten stronger throughout the years.
“We've had some pretty bad years and had some really good ones; him getting his first [solo] podium, his first pole position, his first race win, so that's what builds relationships. That's what builds bonds, is carrying each other through those tough periods and the great ones.
“From my point of view, I'm almost a bit lost as to what's going to happen in the future. Working together with someone for so long, you kind of lose grip on having to learn to work with another driver. You've got to retrain yourself for what the new driver needs.
“You can take for granted the skills and abilities of what a good driver does. There are things I don't have to worry about that Andre just takes care of and does himself. It's easy to take for granted, those abilities, with someone of his calibre.”
Heimgartner has built year-on-year with Kelly Grove Racing, finishing 17th in 2018, 16th in 2019, and 14th in 2020.
With five rounds remaining in 2021, the Kiwi finds himself on the fringe of the top 10 in 12th.
Both Heimgartner and team co-owner Stephen Grove had for some time indicated a desire to continue together in 2022, something Talabani expected too.
Ultimately, negotiations broke down and Heimgartner opted to make the move to Brad Jones Racing.
For Talabani, confirmation Heimgartner would depart came as a shock considering the momentum which was building towards the new year.
“From our perspective, up until when they started discussing the next year, we were all guns blazing for what we were going to do next year,” Talabani explained.
“He was really stoked getting a new chassis, having something nice and fresh for him and then he can carry that on into next year.
“That was the mindset from his point of view and my point of view and this year has been a challenging one, but we've been building on it to really hit the ground running next year.
“We want to try and iron out those inconsistencies so that at the start of next year we could have been smashing it, basically.”
At the year's end, Heimgartner will leave Kelly Grove Racing while Talabani will stay, ending their four-year run together.
Nevertheless, Talabani said he's proud to have worked with Heimgartner.
“I take minimal satisfaction from myself, but I take great satisfaction seeing his profile increase,” he said.
“That's enough for me, really. The age gap isn't enough for me to consider him a son, but that's how I'd imagine that sense of pride.
“To see his value and his performance increase over the years has been down to the work he's put in, the work the team has put in, and the faith the team has put in him, and he's repaid it.
“Yes, there are inconsistencies, but he's been the best performing driver in the team for the past three years.
“It's been great to watch, it's been great to be a part of, and we'll continue to see him rise in years coming.”
Kiwi teen Matthew Payne is the favourite to join David Reynolds in the Braeside squad's 2022 Supercars Championship full-time line-up.