Smudgy fingerprints, seen when screen is off, mostly. I try to be careful. Manual isn't too descriptive-no harsh chemicals, soft cloth. I don't want it to turn into the cure is worst than the ailment.
Would that do the trick for smudgy finger marks? I'd think you'd need a solvent of some sort, but potentially dangerous to plastic.
Try damp cloth first. Our son cleaned his CX-5 touchscreen with some "interior cleaner", left it milky, he resorted to adding a screen protector. Replacement touchscreens can cost thousands, so good to start with the most innoxious possibilities. Or just ignore it?
On my relatively new MacBook, Apple says water-dampened cloth. Doesn't really get rid of fingerprints, but it's not a touch screen either. I'm thinking, if the screen is on, not noticeable, just when off. I kind of like the car display dark, a lot of times though.
Use a tint-safe glass cleaner and spray it onto a microfiber towel - don't spray it directly onto the glass. You can test it in a inconspicuous corner of the screen, if your not sure. I do the same with all my computer screens. Unfortunately, I can no longer 'borrow' those really expensive screen cleaning towelettes, since I've retired. They do require a bit of elbow grease, since the solvents aren't that strong. If there's a layer of dust on it; use something like a swifter to pull that off the screen FIRST; so you don't inadvertently scratch it when applying the damp cloth with elbow grease.
You can use something like Invisible Glass. Spray on to a microfiber towel and gently wipe the screen and done.
I use a microfiber cloth. I also bought this: Helps a lot, the screen is not as sensitive with a glass screen protector to rubbing or damage. The glass does increase reflection a little but it has been a good addition.
That link didn't show up, for me. edit: I did find similar screen protectors on Amazon. I'll give it a whirl. I'll have to give the screen a good cleaning first though, lol.