That means Heimgartner and Michael Caruso could be battling for the second seat in 2019.
"I am trying to do everything possible to get more contracts going forward," Heimgartner told The Herald. "I would love to stay with [Kelly Racing] because they gave me the opportunity to drive this season where other teams didn't.
"Everyone measures themselves against their teammates. Rick has been going amazingly well at the moment – it must be some magic water that he is drinking at the moment because he has been thrashing us."
Caruso sits narrowly in front of Heimgartner on the points' table but that doesn't tell the full story.
Heimgartner has probably been the second fastest of the Nissan drivers this year but misfortune has certainly hampered his ability to score results.
"It has been one of those years," he said. "There have been positives to take away but at the end of the day you would like some results to take away.
"The car speed is there but we just need to have a bit of luck.
"It has been a little bit frustrating in that regard but I suppose it is better to have speed and no luck than to not have any speed."
Heimgartner has had to fight hard to get his chance in Supercars. He was handed a debut drive by now defunct Kiwi operation Super Black Racing. With that seat disappearing the current NZ Touring Car champion moved to perennial back-marker Lucas Dumbrell Motorsport in 2016, which didn't help his career.
"Being in the LDM team in 2016 team half ruined my reputation so getting that back is a massive thing. Last year I managed to do that partly through the Carrera Cup things and then the endurance drive that came at the Gold Coast.
"I think I have proved this year that I can mix it with the top guys."