Makes perfect sense I will use 95 octaneUse the highest octane fuel available. i.e. 95. Altho the engine ECU will possibly adjust to compensate for the lower octane it will probably do this by retarding the ignition this will result in reduced power/MPG. Besides which modern direct injection systems operate to very fine clearances [ injectors/high pressure pump]and the higher octane fuels may contain additives to help with this. What does the local Mercedes concessionaire/ importer advise??