Cleaning matte black decals?

So I have two larger black matte decals that always remain dirty after I go through a car wash (touchless). They are 3m matte vinyl, what's the best way to clean them up after going through the wash? Is it as simple as a soft cloth + rubbing alcohol or should I be getting something a bit more extensive for them?

 

I would recommend cleaning by hand with a waterless wash. No reason to use rubbing alcohol.

 

Perfect, thank you!

 

You always want to start with least aggressive method. Not sure how you are maintaining your paint but I would be on the look out for the decal getting dried out and blotchy looking

 

3m makes a vinyl cleaner/restorer for their products

 

Try the chemical guys matte spray detailer, I use it on my matte finish TE37, as well as the matte decals on the truck. It does a real good job.