– Why are you supposed to put high octane gas in some (typically luxury brand) cars?

Question

– Why are you supposed to put high octane gas in some (typically luxury brand) cars?

In: 21

Answer 1

High octane gas can resist compression better without igniting prematurely. High performance engines use high compression ratios to squeeze more power out of the fuel.
Modern engine control units back off the performance if they detect signs of premature ignition, but older cars could get engine damage from too low octane fuel.