Fuel is a kind of weapon. Why German had no P51? A-bomb? Panic?
B4 is 87#, C3 was almost near to 100/130 especially in late period, ie C3=97/127, sth. like that.
Anyway, before 1944, C3 was no use for Bf109s because of other engine limits.
1944 Spiring, B4+MW50=100/130 and C3+MW50=115/150 fuel.
In WWII, Germans fuel could satisfy their engines without problems. German aircrafts could NOT gain perormance enhencement with allied 100 or 150 fuel.
BTW, USA (Standard Oil company)already provided the lead tetraethyl technology(know how) to 3rd Reich before WWII, and German chemical industry had no difficulty producing high grade fuel. Don't play "fuel" cards. LOL