Driving for the Team 18 Holden squad the 2015 series champion finished last season a respectable 10th in the points, his best race results a pair of fourths in Darwin.
However he was pipped in an enthralling battle with new teammate Scott Pye, who finished the season ninth, just 20 points ahead of Winterbottom.
While Pye was buoyed by impressive race pace, particularly in the second half of the season, Winterbottom’s form trended the other way.
He struggled for single-digit results from Townsville onwards, eighth places finishes at The Bend and Bathurst the rare highlights.
According to Winterbottom the issue was set-up, his car not reacting in the same way as the others in the Triple Eight/Team 18 data share pool.
That tipped him off to a potential issue with the chassis, however, with the team stuck on the road due to the pandemic, it wasn’t possible to properly investigate the issue.
It wasn’t until post-season that the crew were able to return to base and strip down the car, which revealed cracks in the chassis.
“I got back after the time away and said ‘strip my car, there’s something wrong with it’,” Winterbottom told the Below the Bonnet podcast.
“We were really competitive the first four rounds of last year, but then the set-ups and everything turned pear-shaped. We could never copy a Triple Eight car or [Pye’s] car after that. So I knew something was wrong.
“It was more about pulling the car apart, finding problems, and when we found them, fixing them and moving on with it. There were a few little things there and a few little extras we could put on the car for this year to make it the same as [Pye’s] car.
“It’s just how it was last year; when you’re on the road it’s very hard to develop or repair of fix or improve cars.
“I knew, rolling out at the test day [in 2021], what we had would be much better.”
The chassis fix and upgrades has helped Winterbottom to a promising start to the new season, with 11th his worst result from the five races so far.
That’s given him a handy early break over teammate Pye, who is just 14th in the standings, however Winterbottom swears he’s not focussed on on the intra-team battle.
“To be honest I don’t focus on [Pye] at all,” he added.
“I think you’ve got the focus on the bloke that’s winning. We can look at [Shane] van Gisbergen’s data, so at the moment if he can win, I’m trying to beat him. If we beat him we win the race.
“I don’t get into the team/driver rivalry too much. I know if you’ve got the equipment, the results will take care of themselves.
“So it’s not so much motivation, we’re motivated anyway. If you’re not motivated you’d give up. Scott did well last year, but by no means is he my motivating factor. I’ve got enough hunger myself.”