The Japanese manufacturer caused a surprise by registering 52-year-old Sasaki as a third driver for the final test of the pre-season alongside its usual drivers Takuto Iguchi and Hideki Yamauchi in the works R&D Sport-run BRZ.
Sasaki previously drove for Subaru between 2010 and '14, his stint at the team coinciding with its switch from the Legacy to the first-generation BRZ that was only replaced by the current car in 2021.
The 2005 GT300 champion remained a regular driver as late as 2018 with apr, the team with which he won his title, and made his most recent starts in 2020 as a substitute driver with the X Works Audi team.
He remains active in the second-tier Super Taikyu series driving a McLaren 570S GT4 for his own Kota Racing team.
Subaru team director Masahiro Ozawa explained that while there are no plans for Sasaki to race for the squad this year, concerns about the intensity of its regular drivers' schedules - which also include Super Taikyu and a return to the Nurburgring 24 Hours - prompted the move.
"We don’t have any intention of registering him [Sasaki] during the season," Ozawa clarified. "We basically want to carry on with our current pairing. But the two of them are driving for Subaru a lot.
"In April there’s the Nurburgring 24 Hours qualifying race, and then the week after the Nurburgring 24 Hours [in May], there’s also the Fuji 24 Hours. Then a week after that there is SUPER GT [at Suzuka]. It’s a tough schedule!
"Considering that, we thought there is a risk of one of them getting COVID-19 or getting injured. In that situation, there are not many drivers you can call upon, but I think we would go with Kota-san, with whom we are familiar.
"It’s the drivers who have to carry the burden of all the teams’ efforts, so I think to use a driver we don’t have any prior relationship with and say to them, ‘just this time, please!’ is not really our way of doing things."
Poor weather at the Fuji test restricted Sasaki to just six laps at the wheel of the BRZ in the end, all of which came on the opening day.
But even with such limited time at the wheel, the veteran was able to feel how much the Subaru has evolved since his previous stint with the marque.
"Because of the rain I wasn’t able to get to the stage of doing an attack lap, but I was surprised at how much the BRZ has changed in these nine years," commented Sasaki.
"Firstly, the rigidity of the car body felt completely different. Also, unlike before, it uses a transaxle, so the feeling at the rear and the traction are nothing like the past. Compared to FIA GT3 cars, there is little body roll and more downforce.
"The engine is more powerful than before, and the power delivery characteristics have changed, so using the throttle was quite difficult. It was a good experience."
