RE: Engine break-in
All new cars run a knock sensor. You will not hear it unless it is extreme. The car senses knock and the computor retards the timing. That is why you can't feel the loss of power, but you are losing some power through the loss of timing. Run the good stuff and you will get all 400 of those ponies. Run the lower octane and you will lose horsepower, but you will not hear it or feel it. Some newer engines are running in excess of 10:1 compression and for that you will need 91 or better gas for the max horsepower output.