Winterbottom made a historic switch to Holden this year but it hasn't gone to plan for the former Ford hero and 2015 series champion.

The 38-year-old sits 14th in the drivers' standings heading into the final round of the season at the Newcastle 500 this weekend.

Winterbottom finished outside the top three in the championship just three times between 2006 and 2015, but is facing his first year without a podium since 2005.

The man they call 'Frosty' admits his first season driving for Irwin Racing has been challenging in a one-car team but remains confident his best is yet to come.

"You get a taste of what it feels like (to be the best) and that's half the problem because when you win Bathurst and stand on that podium it is such an addictive thing," Winterbottom told AAP.

"You put No.1 on the car and it's the proudest day of your life but when you peel it off and give it back to someone else it's the most demoralising.

"Once you win one championship you want two, three, four. Winning has been great but I still feel like I've got a lot left to achieve."

Winterbottom said he has no plans to retire until his infant son is old enough to watch him win.

"You want your kids to see you be successful and win trophies," he said.

"I'm hungrier than ever but that means nothing, you've got to get off your backside and work - that's the hard part.

"Because the day you're not competitive then you're done. You're doing it to win."

Irwin Racing will expand to two drivers next year when Scott Pye joins from Walkinshaw Andretti United.

"I didn't think one car was going to be so much of a challenge but it is. It takes a bit more time to find answers with testing and all that," Winterbottom said.

"Plus personnel, you've got 14 people versus some of the big teams that have got 80 plus people. Small teams just have to multi task a bit but at the same time it's enjoyable because your role is more crucial.

"There have been challenges but I've enjoyed it and I would not change it for anything. And now we're expanding so everything we've learnt we can put into place next year."

DJR Team Penske star Scott McLaughlin has already wrapped up the 2019 championship after winning 18 of 26 races in his Ford Mustang.

But Winterbottom believes with further parity changes to be introduced next year the Kiwi sensation will be beatable in 2020.

"I don't think he's unbeatable and next year there's a few changes that should even it up a bit more," Winterbottom said.

"They're doing a good job but as you can see in the back end of the year, Triple Eight have actually come on quite strong.

"We can catch him for sure but it doesn't happen overnight - he's bloody quick."

Australian Associated Press