Last weekend at Autopolis, the Inging driver scored his first pole in 35 attempts, and went on to finish third, marking his third trip to the podium in succession.
In the run-up to the weekend, Tsuboi had been identified as Liam Lawson’s biggest threat in the fight for the title by his Mugen crew chief Tomo Koike, who was concerned by the way Tsuboi combined one-lap speed in qualifying and strong race pace at Suzuka.
Come the race at Autopolis, Tsuboi simply didn’t have the long-run pace to convert pole into a win on his 28th birthday. But he remains within 11 points of new series leader Lawson and well in contention for the title, a far cry from his performances last year.
Tsuboi went into the 2022 season as one of the title favourites based on pre-season testing form, but as is so often the case in Super Formula, the season itself proved a different story. Often he would show speed in free practice or in Q1, but too frequently he would he would fail to live up to that potential when it really mattered in the Q2 pole shootout.
His best qualifying performance of the year came in the wet at Fuji, where the knockout format was replaced by a single session due to the conditions. That day he was second, but prior to the final double-header at Suzuka, he only qualified inside the top 10 on another two occasions, in the April Suzuka race (seventh) and in the first race at Motegi (sixth).
Then something clicked: Tsuboi qualified fourth and fifth for the two Suzuka races in October, and while he wasn’t able to finish as strongly, his speed in Q2 started a trend that has continued into 2023, marking the Inging driver out as a genuine contender.
“It’s not perfect yet, but from around Suzuka [the final round] last year, I started to properly understand the factors behind improving the time between Q1 and Q2,” Tsuboi told Motorsport.com’s Japanese edition at Autopolis last weekend.
“It’s not a coincidence; now I am understanding more, the times are improving. It’s not a matter of improving conditions or the set-up direction.
“Now I have found a routine like, ‘if you do this, the time will improve’. I feel like I’ve got a really solid system now and now I can approach both Q1 and Q2 with no hesitation.
“Before I was just doing trial and error, and it was like, ‘ah, that didn’t work’ over and over again. But doing that, I started to understand certain things, and the system took shape.
“My way of thinking before was, ‘that worked in Q1 so that will surely work in Q2’, but that approach doesn’t work. Instead, you have to think about Q1 and Q2 totally separately.”
Although the switch to the more oversteer-biased SF23 may have helped matters, the lack of progress for some of the other ‘understeer’ teams that were touted for big things in pre-season testing, like Nakajima Racing and KCMG, suggests that the change is indeed coming from within Tsuboi himself than any major transformation within Inging.
His race engineer Yoshinari Suganuma appeared to back up this particular theory by saying: “I think it’s down to the driver. We aren’t doing anything special with the car. This year he’s doing a great job of improving his times [in Q2].”
Tsuboi looked to be in a very good position to convert his Autopolis pole into a first win since the final round of the 2020 season, as team-mate Sena Sakaguchi jumped Lawson off the line to give Inging a one-two in the opening part of the race.
But once Lawson had cleared the slower cars of Cem Bolukbasi and Kazuto Kotaka after pitting on lap 13 of 41, it always looked like Tsuboi was going to filter out behind the Mugen driver after his mandatory tyre stop, which he finally made on lap 25.
Had Tsuboi come in sooner to cover off Lawson, it’s possible he may have been overcut by TOM’S man Ritomo Miyata, who eventually passed his SUPER GT team-mate for second place in the closing stages with a bold move at Turn 1 after a caution period.
As Tsuboi put it, “either way we can’t escape the fact the race pace wasn’t good enough”, but falling short of the win shouldn’t detract from what has been a strong campaign so far.
“We need to find the reason why we were slow this time, but it’s my third race in a row on the podium, and we’ve finally showed the speed needed to get amongst teams like Mugen and TOM’S, which are always fighting for the championship, so that’s positive,” he said.
“We have been able to be fast at every circuit so far, so I think that’s a good sign for Cerumo [Inging]. Now we have good momentum, so if the last thing clicks into place, I think we can fight for the win. I want to keep up this strong form.”
The top three finishing order of Lawson, Miyata and Tsuboi is now the same as the top three in the championship, with the convalescing Tomoki Nojiri slipping to fourth as a result of sitting out the Autopolis race after being diagnosed with a collapsed lung.
But it hardly seems a stretch to say that the championship is likely to be fought among this quartet of drivers - and whichever way you cut it, just to be in such a position represents a major improvement on a hugely disappointing 2022 season for Tsuboi.
“I’ve become used to being here [in the top three press conference], and last year I was a long way from being in this position,” said Tsuboi. “I think the fact that I’m frustrated to finish third shows how far we have come.”
