I have the SONAX concentrate used long into my car and am also very satisfied with the cleaning power. According to the last report (from May 1, 2013 - Product Review: Window cleaner) from ACE, however, takes the concentrate plastics most of the 11 tested at Super cleaners, so I will now switch to a different product from the test. This confirming my subjective impression I got from the matte Scheibeneinrahmung my car.