Sharing the drive last weekend, they brought their ex-World Touring Car Championship BMW home first in class 3-4 for 0 to 2000cc cars at the New Zealand Endurance Championship's three-hour race in Christchurch.
For former top karter Arron (44), it was the pinnacle result of a 32-year-old quest to become a national champion.
''I've always wanted a New Zealand title. It was always going to be karting that we were going to come close in,'' he said.
He did manage a national runner-up title on the kart track but then he and Stu were bitten by the endurance racing bug and bought the BMW in 2008.
It initially ran a larger engine, which caused mechanical issues over the years, so the brothers went back to a naturally-aspirated ''little old two-litre'' that produces ''just shy of 300 horsepower [223kW],'' Arron said.
He credited the set-up - shocks, suspension, ''big brakes'' - their slick service crew and a little bit of BMW Motorsport magic for the car's performance, which enabled it to finish ninth overall last Saturday in a field filled with late-model Audi, Ferrari and Porsche GT machinery.
Despite having a ''faultless'' race in which the car ran perfectly, the pit stop was executed quickly and no safety car was deployed over the three hours, Arron said he was a nervous wreck for the final laps.
He did the first one-hour 40-minute driving stint building a gap of four laps over the next class rival before handing over the wheel to Stu.
Worried that a last-minute crash or mechanical issue would rob them of victory, it was with huge relief that he watched his brother cross the finish line, alongside their parents, who attend every race meeting in which the brothers compete.
''It was awesome. The good thing is we did it as a family. My mum [Ann] and dad [Jim] are always there,'' Arron said
Smeg Racing's Simon Evans and Gene Rollinson won the three-hour endurance race in the long-distance debut of the team's newly-acquired current specification Audi R8 LMS GT3.
They completed 129 laps, two more than nearest rivals John McIntyre and Mark Gibson in the Tulloch Motorsport SaReNi Camaro GT3.
Third was the Trass Family Motorsport Ferrari 458 GT3 of Sam Fillmore and Danny Stutterd.
Other Otago drivers to feature in the event included Allan Dippie, who paired with Invercargill's Scott O'Donnell to finish sixth overall in the three-hour event and second in the one-hour New Zealand Endurance Championship race in their current-spec Porsche 991.
Dunedin's Tim Mackersy and Queenstown's Barry finished second in class 2 in their Volkswagen Golf.
