Typically there is a knock sensor on the engine, and ignition timing is retarded when you get knock, may also richen the fuel.
The difference can be 10% or more, depending on driving conditions and fuel, but usually it's cheaper to use premium. Peter _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
