Brown tackled the single-day event in the #11 Kaulig Racing Chevrolet Camaro, invited back by the team after being taken out early in the Cup Series race at Chicago in July.

Amid high hopes, his Portland outing never really got going. Gearbox trouble impacted practice and qualifying, and a change meant he started from the rear of the field.

Brown battled for speed until forced into retirement when a rear track bar mount broke while running on the fringe of the top 20 on the final lap of Stage 2.

The reigning Supercars champion also struggled with a failed cool suit and dubbed it “probably my toughest and worst day racing”.

Speaking in a vlog documenting the day, Brown suggested the issue with the rear of the car was likely present from at least the beginning of the race.

“In quali and that I was saying it felt a bit weird, but in the warm-up laps to start the race I was saying, when I accelerated, it was pulling to the right and didn’t feel right,” he said.

“I guess it was unfortunately happening for a while and just had no pace. A disappointing end, that’s three runs in America and three DNFs, so not going very well there.”

Brown’s Cup Series debut with Richard Childress Racing at Sonoma in 2024 was beset by electrical trouble that hampered the car in qualifying and ended his race.

The 27-year-old has expressed a desire to return to NASCAR next year, although what opportunities he will have are unknown amid Triple Eight’s switch to Ford.

Fellow Australian Jack Perkins starred in the Portland Xfinity event, running third aboard the #19 Joe Gibbs Racing Supra when a mistake put him off track in the dying laps.

Perkins explains ‘gut-wrenching’ moment he lost NASCAR podium

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