true, i see better mpg using cars on premium than regular. i guess cuz the slightly more power u get, the less throttle u use, less gas u use. end of the day it prolly evens out but i like having the extra response on tap.

if carburated and OBD1 cars use anything other than recommended, they will cause damage because there is nothing to detect knock or wrong mixture. too much fuel or too much octane can cause the cyliner to cool too much and warp. these cars need mixture tuning, timming, etc, if you want to change fuel type.

OBD2 cars have more programing, they can detect knock and adjust the amount of air/fuel mixture and timming automatically adjust, so this will not cause damage.