In only its second outing in the WEC’s top Hypercar class with the Porsche 963, Proton proved competitive as the car shared by Jani and team-mates Harry Tincknell and Gianmaria Bruni ran in the top five just shy of the two-hour mark.
However, the team’s hard work was undone when Tincknell came in after his opening double stint to hand over to Bruni, as a problem occurred with the seat belts that forced Proton to take the car in the garage for more than five minutes.
As a result, the #99 machine lost seven laps to the leaders, and finally ended up classified ninth and eight laps behind the winning #7 Toyota GR010 HYBRID.
Post-race, Jani lamented a lost chance to beat the Ferraris, as Tincknell had been hassling the #51 499P started by James Calado before his doomed pitstop.
“A lot was possible,” Jani told Autosport. “When I got in the car I was just behind the [#6] Porsche and the two Toyotas, and I stayed behind them for the full stint.
“The belt came out of the buckle - where you tighten the belts, the part you pull to tighten it, it went through the buckle and came out.
“We couldn’t tighten the belts anymore, so we had to change the whole belt. It was a proper freak event. I’ve never seen anything like that.
“It’s a shame, because I’m sure we would have finished fourth. We were quicker than the Ferraris, we had them on pace.
“But if you consider the car was new this weekend, it’s exactly these things that can happen when you don’t test beforehand.
“We saw that we have the drivers, and we have the pace. Now we just need to sort out the details that are just logically not sorted yet with so little running time.”
The Porsche 963 chassis that Proton raced at Fuji was different to the one with which it made its Hypercar debut at Monza in July, which was then shipped off to the United States to contest the IMSA SportsCar Championship.
As was the case with the team’s first chassis prior to Monza, the only running conducted prior to Fuji with the second car was a 10-lap shakedown at Porsche’s Weissach HQ.
Tincknell added: “It sucks because it was going so well. I had been right behind Calado before stopping. I had a really good second half to my stint and we were there with the Ferraris.
“The pace of the car was amazing given that we’ve done no testing. We're making steps all the time and I think our P5 in FP3 was genuine.
“I really think we are punching above our weight, given that Proton isn't an established prototype team and where we are in the programme.”
Proton’s fellow Porsche customer squad Jota was also left lamenting the chance to beat an off-colour Ferrari at Fuji.
That was after Antonio Felix da Costa picked up a drive-through penalty for making contact with another car - ironically, Jota’s LMP2 entry - at Turn 10 in the second hour while running fifth.
The penalty resulted in da Costa, Will Stevens and Yifei Ye slipping to an eventual sixth behind both of the Ferrari 499Ps, 22 seconds down on the fifth-placed #51 car.
Jota boss Sam Hignett told Autosport: “Without the drive-through, we would have been fighting for fourth with the lead Ferrari.
“The final result is warped as well because they ran the FCY for less than a full lap and we did the whole of the straight under FCY.
“We lost 15 seconds there, so in reality we were about 10 seconds behind [the #51]. We could have been P4, but we were missing a bit to the #6 [factory] Porsche, so a bit of work to do there.”
