The E4 series had 100 octane gasoline
From Wikipedia
http://de.wikipedia.org/wiki/Messerschmitt_Bf_109
Bf 109E-4 fighter aircraft, engine such as E-1, new cockpit cover as standard, armament 2×7.92× -mm gun, two 20mm MGFF/M in the wings
Bf 109E-4/B fighter-bombers, engine such as E-1/B; weapons such as E-4, up to 250 kg bomb load
Bf 109 E-4/Trop: fighter and fighter-bombers, such as E-4, with additional features tropics (sand filter, auxiliary equipment)
Bf 109E-4/N: fighter, such as E-4, but DB 601N engine with 1020 PS, higher compression,
100-octane gasoline-C3
Bf 109 E-4/BN: fighter-bombers, engine and armament as E-4/N, up to 250 kg bomb load
If you want gasoline octane 100
I want a BF109E4/N(BN)
