always found optimax to add zing in the cars stride personally, and in one of the evo issues they put cameras down the spark plug holes before and after. BEFORE.loads of tar on the valves etc,
AFTER. valves clean as a whistle and spangly!
all in gear times were up on all cars tested too. mcoupe, xjr, ctr, + other
so as fuel can swirl correctly in to chamber then it can mix good and therefore burn as it should. more bang per spray equals better mpg overall??as working more efficiently etc..
bp looks like same stuff to me. ( and both of them are cheaper then super around here) so theres my two peneth.
dan