SUPER GT's GT300 BoP process is too simplistic, says apr

SUPER GT's Balance of Performance in the GT300 class is too simplistic and doesn't properly cater for outliers such as the outgoing Toyota Prius, according to apr boss Hiroto Kaneso.


The organisers of the Japanese sportscar series face a tricky task balancing three types of cars in the GT300 class, with FIA GT3 machinery mixing it with cars built to SUPER GT's own GT300 rules (formerly 'JAF GT300') and 'Mother Chassis' cars based around a standard chassis.

One model that has struggled in particular in recent seasons is apr's hybrid-powered Prius PHV GR Sport, which is now in its fourth and most likely final season of competition in its current front-engined guise.

Apr scaled back to a single example of the car for 2022 as it brought in the new GR86, and is known to be working on an all-new Toyota model for next year that will effectively replace the remaining Prius in its line-up.

Kaneso feels that one of the reasons that the Prius has been unable to perform is the fact that the tools available to the rulemakers when it comes to setting the BoP are so limited, especially in comparison to the more sophisticated methods used by the SRO to set the BoP in FIA GT3.

He hopes a way can be found to make the BoP more inclusive for a wider variety of cars in future.

"In SUPER GT, the only things they can adjust are the power of the engine and the weight of the car," Kaneso told "They are the only things that are considered. Things like the amount of downforce produced are not measured.

"Only cars with sportscar-type bodies like the GR86 and Supra can do well in this championship.

"Personally I’m a big fan of the Prius and I would have liked to continue with it, but with the current regulations we just can’t show any of the car’s positive attributes. If we were racing under SRO GT3 rules, it would be a different story, their rules are really great.

"It’s because their BoP is so good, so many manufacturers are able to do their own thing and enter different types of cars. It’s so cool we can see Ferraris racing against Bentleys! The Bentley [Continental] wouldn’t be competitive here, just because of the body shape.

"That’s something I’d like to see change in the future. If it’s just Supras and GT-Rs in the future, it’s boring. The fans want to see a variety of different cars competing together.

"It’s difficult to create a BoP that can allow for that, so I don’t want to complain about the GTA, because we also have the different tyre manufacturers, but we need to take the next step with the BoP."


Apr's current front-engined Prius did manage to take one victory last season at Autopolis, but that came after a BoP adjustment that allowed the #31 car shared by Koki Saga and Yuhki Nakayama to run with larger air restrictors, which was immediately reversed for the next race.

The Prius was then saddled with even smaller air restrictors and more weight this year as part of a drive to slow down the GT300-spec cars in comparison to the FIA GT3 runners.

Kaneso said that these changes and the fact the team is now only running a single Prius has made its job much harder in 2022.

"The BoP changed, and the engine [power] and the hybrid system have to match," he explained. "We don’t have much running time and we are spending all of our time working on the engine mapping.

"We don’t have a dedicated test team that can continually test, we have to gather the data on the race weekends and we are really struggling.

"It's also difficult with only one car. Last year we had two Priuses, but now we can no longer compare the data between the two cars."

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