A lot of us here simply use regular unleaded and it has no significant effect on the engine's power or idle running. I think the regular is 92 here and the premium is only 94. Some stations do offer a higher octane to 96 or 98 I am not so sure. For Benz engines they reccomend at least 92 which means regular is ok, but 94 or higher will be even better. But is premium really necessary? I am referring to the family cars and not the AMG or SLK and CLK varieties.