The defending champion suffered a fractured leg and wrist while three volunteers were also injured in the terrifying incident at Mount Panorama.
Video: Chaz Mostert's horror crash at Bathurst
His season is now over but the 23-year-old didn't lose his sense of humour in the worst crash seen at the famous track in several years.
"Thank God we signed that contract a couple of months ago," he told Prodrive Racing team boss Tim Edwards after the crash, according to v8supercars.com.au.
"He is in good spirits, but I think there is a bit of green stick (pain killing drugs) in that," Edwards added.
"He is thinking of the team and very apologetic to the boys who put in all the hard work to get him out on the track."
"But it was good he was able to joke and I am happy to let everyone know about it."
Mostert, who has five victories this season, signed a lucrative deal until the end of 2020 earlier this year.
Team-mate Mark Winterbottom told v8supercars.com: "One of the things he said just as they souped him up with morphine was 'sorry to the guys that he crashed' and 'make sure Frosty gets pole'.
"That's the sort of kid he is, he's a good kid and you don't want to see that, it's not good at all … results or whatever, you don't want to see one of your friends get hurt. It's really bad to see.
"He's in good spirits, he’s a good kid."
Winterbottom admits the crash is a major reality check ahead of the big race on Sunday.
"It definitely reminds you how dangerous this joint is, so, yeah, it’s not good," he said.
"You give your kids more of a hug, because it’s reality.
"So it's unlucky and lucky at the same time because that’s a big shunt. At least, he doesn't walk away from it but he can actually talk about it, which was good.
"And the marshals as well, they put plenty on the line.
"It's just a reality check really – that's why results wise, whatever you've got to forget about that, it's about the big picture."