5.7% of the fuel blend must be biofuel (something that a manufacturer has commercial intent to supply to the public)
the clear candidate for this job is bio-butanol or something made from bio-butanol
butanol has less than 80% of the heat value/kg that gasoline has
if (bio) butanol was 5.7kg of race fuel blend that 105 kg contains the same heat as 103.6 kg of fuel blend without bio-ingredient
but a bio-fuel ingredient with the same heat value as gasoline would give ....
105 kg of race fuel blend containing the same heat as 105 kg of fuel blend without bio-ingredient
1.5% more heat than if butanol was the bio-ingredient
ie 1.5% more power for the same time (or the same power for 1.5% longer)