Poor idle, engine misfires, or reduced fuel economy sound familiar? Changing your spark plugs might just be the answer. Over time the electrode will degrade and can see a build-up of carbon which weakens the spark. Spark plugs are responsible for igniting the fuel, so a clean spark is required to ensure you're getting the best performance and fuel economy from your BMW. These Double Platinum spark plugs are from original equipment supplier Bosch, and are the same spark plugs that BMW fitted at the factory.