Just to briefly reiterate. HIGHER OCTANE FUEL DOES NOT BURN SLOWER!!! The octane rating of a fuel is a measure of its detonation resistance. Detonation is the sudden reaction of the unburned portion of the partially burned fuel-air mixture rather than being consumed by the normal flame front propagation. Somehow this gets obsfucated as "premium gas burns slower". NOT TRUE!

Detonation creates high pressure shock waves in the combustion chamber, which vibrates the engine structure and this is the "knock" or "ping" we hear. These shock waves increase heat transfer to the combustion chamber boundary by up to an order of magnitude, so sustained detonation can rapidly overheat pistons and valves, which can lead to structural failure of these components.

Octane is primarily determined by the blend of hydrocarbon species in the fuel. Prior to the banning of tetraethyl lead (TEL), it was used in small concentrations to boost the octane rating of a gasoline blend, thereby increasing detonation resistance, but today, refiners have to juggle octane rating and Reid vapor pressure purely by the blend of components in the fuel. Aromatics - ring shaped hydrocarbons - such as benzene used to be used liberally to increase octane rating, but they are considered to be carcinogenic, so their quantities are now limited, and Reid vapor pressure is regulated to reduce evaporative emissions.

All of the above consipires to raise the price of producing gasoline that meets the octane and myriad regulatory requirements, which is the big reason why gasoline prices are heading up across the country, and California's unique "RFG II" blend is the most expensive to produce.

Duke