Does anyone know roughly what percentage of allied fighters used 150 octane toward the end of the war?  Was the 150 octane widespread and common or just something that existed but was rarely used.  What about for the axis fighters.  How widespread was the C3 (or whatever it is called) used late in the war?
Any Fw190 powered by a BMW 801 engine required C3 fuel. Me109s used mostly B4 fuel. Best to take anything Kurfurst had to say with a very large pinch of salt.
As for 150 fuel,
Consumption of 150 Grade Fuel - Barrels
        UK consumption   North West Europe
    June 1944   184,000 (25,205 tons)
    July 1944   283,000 (38,767 tons)
    August 1944   218,000 (29,863 tons)
    September 1944   169,000 (23,150 tons)
    October 1944   183,000 (25,068 tons)
    November 1944   140,000 (19,178 tons)
    December 1944   193,000 (26,438 tons)
    January 1945   138,000 (18,904 tons)   of which 15,000 (2,054 tons)
    February 1945   148,000 (20,273 tons)   of which 17,000 (2,328 tons
    March 1945   201,000 (27,534 tons)   of which 52,000 (7,123 tons)
    April 1945   208,000 (28,493 tons)   of which 89,000 (12,191 tons)
    May 1945   49,000 (6,712 tons)   of which 32,000 (4,383 tons)
    UK = 8th AAF and ADGB. Northwest Europe = 2nd TAF.
    Other figures.
    August 1944   USAAF 182,000 (24,931 tons)   RAF 49,000 (6712 tons)
    October 1944 estimated   USAAF 225,000   RAF 45,000
    December 1944 issues   USAAF 133,000   RAF 0
    December 1944 exports   USAAF 8,000   RAF 88,000
    December 1944 issues on continent.   USAAF 0   RAF 13,000
    7.3 Barrels = 1 ton.
    Data from POWE 33/990 33/991 33/992 33/985 
http://www.wwiiaircraftperformance.org/150grade/Consumption_150_Grade_fuel_Barrels.html