The ByKolles-run squad returned to the WEC this year with the non-hybrid Vandervell 680 LMH, the successor to the troubled CLM P1/01 LMP1 car that failed to finish Le Mans 24 Hours in six successive attempts.
Vanwall’s season so far has been plagued by a number of reliability issues, most notably a brake explosion at Portimao that led to Jacques Villeneuve’s race-ending crash and an engine failure at the Le Mans 24 Hours that forced the team into another retirement.
In the previous round at Monza, the team also lost a chunk of the time in the pits to clear brake ducts amid overheating issues, leaving it 20th - and behind eight LMP2 cars - at the finish.
However Guerrieri, who has been part of the Vanwall LMH programme from its inception and is the only driver to have taken part in every race with the team in 2023, explained that the Vandervell 680 is gradually turning into a reliable machine and has encountered no major technical problems recently.
“During Monza we didn't have any big reliability issues and so far this weekend [at Fuji] as well,” Guerrieri told Autosport. “So in that area we are doing pretty good.
“There are little things here and there, like today [Friday] we had an issue with the steering rack, probably [ran] over a kerb or something.
“Things can happen, we assess this as an issue as well. But [the reliability is] looking much better.”
Asked if that meant Vanwall could now put more effort into extracting more speed out of the car, Guerrieri said: “We don't have any reliability issues, definitely yes.
“Performance-wise and set-up we have been trying different directions. But it looks like there might be more structural issues or problems that we need to improve and it's not only around the set-up.”
Source: Autosport