Dirt, mud, sand, snow, ice or anything and moisture develops and builds up on the bottom of the doors. You open the door to get out and at the bottom of the door it is loaded with whatever road debris is on the road. Area is open to spray from the road so of course all the elements are stored at the bottom of the doors which will cause premature rust from this. Constantly need to keep clean. Worse than changing a baby's diaper. Design flaw. Have now found other owners complaints from 2014 models. Apparently same problem and no fix.