The knocking or pinging sound may be more noticeable when accelerating or climbing hills. If you hear knocking, it could, over time, damage pistons and other engine parts. If your car has a knock sensor, it will compensate by slowing spark timing. Your engine will be protected, but possibly at a slight and sometimes noticeable loss in power and acceleration. Roughly half of today's vehicles are equipped with knock sensors.
Most cars give optimum performance on regular or mid-grade gasoline.
If you're buying premium and your car's not running any better than it does with a lower-octane gasoline, you're probably wasting money. However, some cars may operate better on premium because of additives. Additives, which are found in all gasolines, keep engines clean and make them run more efficiently. Some brands have more effective additives and some use bigger doses in their premium grades. Driving habits, a vehicle's mileage, and climate and geography can affect how gasoline performs in your car.