Thanks Duke for asking the year and model.

Once the timing is retarded when knock is sensed, not only will power suffer, but also fuel consumption will increase.

Even though gas prices are higher, the cost difference between regular and premium is still the same. So, the percentage difference between regular is lower. Using lower octane fuel will cost about 10% less, but your fuel mileage will suffer.

Since you didn't tell us what year and model you're driving, what I said is assuming that you have a mid eighties or newer car with a knock sensor.

Sorry Paul, but the reason that the ignition is retarded upon sensing knock is to PREVENT engine damage, particularly piston tops.

Have a great day,