Spark Plugs

Hi Dave Many thanks for info As I'm coming up for a service the BMW dealer told me there would be a spark plug change which I questioned. My car is Turbocharged but only cover 4 or 5 thousand miles ayear. The car is going lovey no problem so I will still have the schelual with out spark plug change . Geoff

Is it necessary to change spark plugs at 18000 miles I have had the car from new