Reigning champion Sho Tsuboi topped both days of the test earlier this month in the #36 car he shares with Giuliano Alesi, setting a best overall time of 1m18.116s on the second day of running.
By comparison, the KeePer-branded #37 car was down in ninth on the combined timesheets courtesy of a 1m18.422s set by Miyata on the opening day, around three tenths off the pace of Tsuboi.
But TOM'S newcomer Miyata insists he isn't worried by the gap between the team's two cars at this stage.
"I always had GT300 class traffic and I can’t make a good attack lap," Miyata told Motorsport.com. "I checked the on-boards and data, it seems the #36 had a clearer attack lap and they gained some time.
"I think the #36 and #37 have about the same potential. Of course Tsuboi-san is the reigning champion, and it’s my first time on Bridgestone tyres [so a gap is normal]."
Fenestraz admitted to "messing up" his flying lap during the 10 minutes of running reserved for GT500 drivers at the end of Saturday, further muddying the picture, but is confident of the #37 car's race pace.
"We’re never using the same tyres as them [the #36]," the Franco-Argentine driver told Motorsport.com. "I do think we are there, we are pretty even.
"Pure performance on one lap, I’m still not able to put everything together, and Sho has a lot of confidence from last year and he managed to put it all together. I think if we can do the same, we can be competitive.
"Sho is a little bit ahead, but it doesn’t mean we can’t reach his level. We’re just slowly building up and working hard to be at his level, because Sho is really fast, he has been flying."
Miyata relishing Bridgestone tyres
Miyata is going into his third season as a GT500 driver, having raced up to now for the Racing Project Bandoh team - the only member of the Toyota GT500 stable that uses Yokohama tyres.
Barring a one-off outing with TOM'S back in 2019, when he was substituting for an absent Kazuki Nakajima, this season therefore marks Miyata's first on the championship's benchmark Bridgestone rubber.
Miyata admitted that he was "surprised" by the performance on offer with the Bridgestones, and also said he his relishing being able to share information with five Toyota teams on the same tyres.
"Yokohama and Bridgestone have a similar feeling for a short run, I think the peak grip is about the same, but the warm-up is so different," noted Miyata on the differences between the two tyre makers.
"The main difference is the long run, Bridgestone is very strong and they always get strong results. The tyre has no problem [even after many laps] and I can make fast laptimes, so I was surprised.
"Also with five Toyotas using Bridgestone, every session we have information about what the other teams are doing, but at Yokohama we couldn’t do that. It's very different to last season."
