1. M

    What octane for 2.5L normally aspirated Z3

    I’m in California and have the choice (typically) of 87, 89 and 91 octane at US $4.60, 4.80 and 4.90/ gallon respectively. Each is ”up to 10% Ethanol” Is there a benefit to the higher octane fuels for my 2000 z3 2.5L engine? I don’t have the owner’s manual. thanks, Matt