how bout some wood glue to fill the cracks and sanding paper to smooth it out. i have the vertical crack along my long dash trim as well, it was there when i bought my car too but i didn't notice it when buying it its one of those things you can only spot in certain lights. any way i plan on redoing my trim in a few days but im going with vinyl and i think im just going to fill the crack and sand it down before i begin wrapping. although my crack isn't deep at all its only surface

 

thanks for the tip but these are very lighhts cracks i barly feel the with my fingernail