They lead a life in the shadows, but they are more important than any luxury accessories: Filters. Filters purify the substances that are necessary for proper engine operation. Neglecting replacement intervals or using poor quality filters often result in substantial costs down the line. Filtration has become very extensive in modern vehicles due to the constantly rising requirements on the engines. High customer demands as well as stringent environmental regulations are further factors that have a great influence on the development of filter technology.