The Japanese series announced last year plans to switch to a second-generation biomass fuel supplied by German firm Haltermann Carless for the 2023 campaign as part of a drive to reduce carbon emissions.
Teams sampled the fuel in a post-season test at Motegi after the final round of the season last year, but difficulties in supply mean most manufacturer testing over the winter has been conducted with regular gasoline.
Engine development is likely to be a major focus for GT500 marques Honda, Toyota and Nissan this year with aerodynamic development frozen for the upcoming season.
Impul Nissan driver Baguette believes that the shift to carbon-neutral fuel (CNF) has the potential to shake up the competitive order.
"The aero is frozen, but there’s a big change coming with the CNF," Baguette told Motorsport.com. "We have to see how the different manufacturers adapt to that. It hasn't been used so much over the winter, so we have no idea yet who seems to be more impacted.
"The tyres will be a factor like always, but I think the key factor will be the engine and adapting to CNF."
Manufacturer testing has so far been dominated by Honda, which has topped every one of the five days of running that has taken place this year with multiple GT500 marques in attendance.
But TOM'S Toyota driver Ritomo Miyata says the impending switch to CNF means that the real picture won't become clear until official pre-season testing kicks off next month.
Miyata told Motorsport.com: "So far I didn’t really feel an improvement with the [Toyota] engine, and Honda has always been the fastest in the timesheets, but we don’t know what will happen when we start using this CNF.
"I think all three manufacturers were using normal fuel [in the most recent test at Okayama]. But we need to know the character of the CNF and how it will impact the engine’s driveability. It could be quite a big change from normal fuel, so we need to learn how to use this properly."
Baguette relaxed about apparent Honda advantage
While Hondas dominated the timesheets in this month's Okayama test, the #1 Impul Nissan of Baguette and Kazuki Hiramine was fifth-fastest across the two days, albeit with a best time more than six tenths of a second shy of the pace-setting Real Racing NSX-GT.
But Baguette insists he is relaxed about the apparent advantage that Honda has at this stage, and is confident that warmer weather will bring both Nissan and Toyota back into the picture when the season kicks off at the former Pacific Grand Prix venue in April.
"It’s always better to be at the top for sure, but we will never race in these kind of conditions, starting in the morning with 1 or 2 degrees Celsius," he said.
"Honda gets more of an advantage than the others in these conditions because of the aero. For now they look fast, but I don’t think they will be four, five tenths ahead in the first race. I’m sure that like every year, all three manufacturers will be close again this year."
Baguette and Hiramine endured a difficult start to their title-winning campaign at Okayama last year as they finished seventh on what was the debut race outing for the all-new Nissan Z.
The Belgian is confident of a stronger showing this time around, although he was also keen to point out that no driver pairing had clinched the title after winning at Okayama since Nick Cassidy and Ryo Hirakawa for TOM'S in 2017.
"When everyone was running new tyres [in Session 3], we were three tenths off the best time, which is not that bad," said Baguette. "And last year [in the race] we were running in P2 for a long time, and without the pick-up issue we had, we probably could have finished in that position.
"I don’t think we are the strongest car in Okayama, but sometimes with the way this championship is structured [with success ballast], it’s better if you don’t win at Okayama! If we are not that competitive there, I won’t worry too much."
