Yamashita struggled to match Fenestraz during their second full season as teammates in 2022, ending up a lowly 15th in the championship while his teammate finished as runner-up to champion Tomoki Nojiri, also giving the Toyota-powered Kondo squad a first win in three years.
But with Fenestraz exiting Super Formula to race in Formula E with Nissan, Yamashita was afforded the chance to try out the Franco-Argentine driver's #4 car (renumbered as the #3) in the series' annual two-day rookie test.
Driving the car marked out by the distinctive green highlights on the front wing and mirrors, Yamashita was an encouraging second-fastest on the opening day of running, before concluding the test eighth overall.
"From the start of the test the feeling was good, and the laptime was good, so it feels like it’s better than the car I used this year," Yamashita told Motorsport.com. "It’s easier to drive than the car I had this year.
"I knew the balance would be different [using Fenestraz’s set-up], but I didn’t know what the difference would actually be, and I was worried whether I would be able to adapt to it. But when I tried it it was fast and easy to drive.
"It’s pretty different, more so than I imagined, to the extent I didn’t think was possible before."
As well as swapping chassis, Kondo also reassigned its two race engineers for the Suzuka test, with Yamashita working with Fenestraz's engineer from this season, Takuji Murata.
Fenestraz's replacement Kazuto Kotaka was 16th-fastest on both days of the test under the auspices of Kazuya Abe, who has engineered Yamashita since 2020 and also took Naoki Yamamoto to his first two titles at Team Mugen.
Yamashita said of the swap: "Abe-san and Murata-san have a similar way of thinking, and although they have different ways of proceeding with the set-up, we’ve been able to communicate well and I think we made a step since we started running."
It appears likely that Yamashita will work for Murata on a full-time basis for the 2023 season.
Kotaka will embark on his first season as a full-time driver in 2023 with Kondo after winning this year's Super Formula Lights title, but already has top-flight experience from standing in for Kamui Kobayashi at KCMG in 2021.
Yamashita is confident that he and Kotaka will be able to maintain the team's positive recent form, which followed a disastrous 2021 season when Fenestraz was mostly absent due to visa problems.
"Kazuto was fast when he was at KCMG, so we’ll continue to work together to improve things," said Yamashita. "The atmosphere was bright when Sacha was here, but next year will be my seventh year with the team, so we are all good friends and I don’t think that will change.
"My seat will be in danger if I don’t get some good results next year, so I want to make sure we are able to fight for the championship."
