There is a popular myth that higher octane in fuel gives you additional power - it does not. Premium gasoline has the exact same energy content as regular (about 111,400 BTU's per gallon).

The ONLY thing the higher octane is needed for is engine knock. High-performance engines are more sensitive to the octane level because they have higher compression ratios, so they tend to knock on lower octanes.

Plus, the computers in today's engines also detect knocking and will adjust the spark timing and other settings to control it.

There is also a claim by some people that they put premium in once in a while to "clean out the system". Most of the time, the detergents suppliers put into their fuels are the same in all grades.

So in reality, most cars on the road today need nothing more than the regular old 87 octane fuel.