The Japanese single-seater series' 2023-spec car, an updated version of the previous SF19, features revised aerodynamics aimed at reducing downforce and making it easier for cars to follow each other closely.
However, a number of drivers have said, based on their experience of following other cars during this month's pre-season test at Suzuka, that the changes have not made a big difference in this regard.
B-Max Racing's Nobuharu Matsushita was among those to voice such an opinion, although he noted that the slipstream effect has increased as a result of an increase in drag with the new aero package.
"The dirty air is the same, if anything it’s more," Matsushita told Motorsport.com. "When you’re on an attack lap, and you see somebody in front, it’s already affecting the downforce a lot. I’m not sure we can stay closer to them.
"The efficiency is greater with the tow. But more tow means more [dirty air] effect in the corners. That’s what I feel in the corners."
Both Dandelion Racing's Tadasuke Makino and Ukyo Sasahara, standing in for an injured Kenta Yamashita at Kondo Racing, echoed Matsushita's opinion regarding the increased slipstream effect of the SF23.
Makino told Motorsport.com: "The drag is massive. When I was following another car, the tow was huge, so we can slipstream a lot. But still we lost a lot of downforce in the corners.
"I don’t know exactly how it will work in a race situation, but maybe it’s going to be difficult."
Sasahara added that the increased slipstream could work well at Fuji with its long start-finish straight, but less so at other tracks: "The drag means at Fuji there could mean more battling on the straight, but in the corners maybe not."
One characteristic that many drivers have noted with the new SF23 is a comparatively large loss of rear downforce compared with the front, shifting the balance of the car towards oversteer.
Tomoki Nojiri said he feels this change means getting the traction out of slow corners necessary to challenge the driver in front will be difficult.
"When you enter a high-speed corner like Turn 1, the grip is good, but it’s easy to lose the rear in slower corners," explained the two-time champion. "That's a characteristic that I personally doubt is going to create better racing.
"Even if the loss of downforce when following another car is lower, there isn’t that much downforce overall, so I think it will be hard to get good traction."
Additional reporting by Kenichiro Ebii
