I'm kind of confused, If California is so "emissions conscious" then why is the highest octane rating that you can get there 91? I was always under the impression that the higher the octane rating, the cleaner the emissions. BP also advertises this fact about their 93 octane fuel on our local radio stations. Does California fuel have other additives that clean up the emissions of the 91 octane? Can't they do the same thing with 93 or 94 octane? Please enlighten me.