I use Son of a Gun protectant when detailing the interior, and have been for years. A lot of people on here do not like this product because it does have a tendency to leave a residue especially on our interiors. With my MZ3, I wipe the interior with a microfiber sprayed with Son of a Gun, and then I wipe down with a clean and dry microfiber. My dash stays rather clean for a couple of weeks. I also tend not to roll my windows down very much at all other than tilt the sunroof open for ventilation periodically.