I have been using NGK plugs on an M110 engine now for about 5 years and I have absolutely no complaints. I originally installed them because Bosch no longer makes my size of plug in non-resistor, which is essential for MB engines due to the resistor plug connectors. However, I doubt wires and connectors have anything to do with your gas mileage problem. When these go bad, itīs usually indicated by missing and normally itīs the fault of the connectors and not the wires.

I agree the other guys who say use only OEM for cap and rotor.

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