At Fuji, the #6 winning
Toyota covered 1113.7km over the 6 hours. The winning #26
G-Drive covered 1017.5km.
The average speed of the
Toyota was 185.2kmh, the
G-Drive was 169.2kmh.
So if the Toyota lost a half hour, it'd be out
92.75km. The total difference Toyota over G-Drive was
96.2km 
So there would be
3.45km difference. Or a little bit less than 1 full lap of fuji, which is 4.5km!