It was announced on Saturday ahead of the first round of the season at Okayama that the #8 ARTA NSX-GT shared by Toshiki Oyu and Tomoki Nojiri would have to serve a five-second stop-and-go penalty during the race as a result of an authorised chassis change.
SUPER GT rules do not permit GT500 cars to change chassis except in cases of force majeure, such as after a major crash.
However, during the first official pre-season test at Okayama in March, Nojiri said the Mugen-run ARTA team had noticed strange behaviour with the #8 car when trying to run comparisons with the sister #16 NSX-GT.
Honda's SUPER GT project leader Masahiro Saiki explained that subsequent inspection of the chassis confirmed the team's suspicions that the car had not been tracking properly on the straights.
"Car #8 has been suffering a problem of veering on the straights, with the amount of correction required on the steering getting larger as the speed increases," explained Saiki after qualifying.
"This year, Mugen took over maintenance, but matters didn’t change, and even after changing some peripheral parts, the same problem occurred.
"It was not only giving the drivers a bad feeling behind the wheel, there was an element of danger because we could not predict what would happen, and there was a chance of causing trouble to another competitor.
"Some time before the opening race we sent the monocoque off to the manufacturer for inspection. They confirmed the problem, but because there was not enough time to solve the issue before the opening race, we took the decision to change the monocoque."
A wild, rain-affected race allowed the #8 machine shared by Oyu and Nojiri to catch up to the back of the field after serving its penalty early on and eventual score an unlikely podium finish in third place.
Oyu effectively gained six places during the first full course yellow period and safety car, but strong pace carried him all the way to third before pitting to hand over to Nojiri and equip slick tyres on lap 41 of 62.
Nojiri ran fifth after that round of stops shook out, but gained one place back when the #36 TOM'S Toyota dropped out of second with a loose wheel, while also beating the Rookie Racing Toyota out of the pits for the final podium spot.
However, both Oyu and Nojiri feel it would have been possible to challenge the NISMO Nissan Zs that finished first and second had the race not been curtailed by a series of red flags amid worsening weather.
"Without the red flag, I think we could have fought for the win, and considering we had the penalty, I don’t think we could have done any better, so I’m delighted," commented Oyu.
"I was able to catch up while managing the tyres well, so this is a really encouraging trend for the future. There were quite a few Bridgestone teams struggling, but having the pace to rival the Michelin cars was great."
Nojiri added: "The first safety car was perfectly timed for us, but Oyu set an amazing pace after that. He did a great job overtaking cars, and the strategy worked out perfectly.
"I think we could have aimed for first or second [had the race resumed]. We thought it would rain again, so we had gone for softer tyres that would allow us to fight in those conditions."
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