cleaning rubber trim below exterior window
 

2013 mazda 3. what can i use to clean the rubber exterior? appears to be dirty even after a car wash.

The rubber might not be dirty but could be dry rotting already (especially if you live in very hot/sunny climes tha speeds up the process. You can use special commercially available treatments on it to try and bring it back to looking good, but when they trim is already dry rotting, it just turns ugly again after a short time and replacement might be your only recourse.