Hi Andrew, did you ever get this issue resolved? I am going through the exact thing with my brand new mb cla250. I followed mb exact directions on thier long term matte paint sealer. I got the streaks and it wont go away. They told me to use the mb matte quick cleaner and intensive cleaner still doesnt work. I escalated this to mb corp office. Still waiting to hear from them. I apprecaite your thoughts.