The purpose of higher octane fuel is to prevent pre-ignition (knocking) caused by high compression ratios. That's it folks. Unless you are running a high compression engine, such as a Corvette, it is not necessary and a waste. The Civic does not have a high compression ratio engine. Regular and Premium explode with equal intensity when sparked off with the engine's spark plug. One is not more 'powerful' a fuel than the other. However, Premium is engineered to resist ignition simply by being compressed.