something that can make an unbelievable scene is introducing/ mixing real materials with representative.
it's accepted your vehicle is not sheet metal, but when you place it in front of a stone wall made with pebbles you found last summer on vacation, the wall looks fake.
too much detail can blow it, also. another hot debate is to make nail holes or not. a good guideline is the 12' rule. if it could not be seen from (real 1:1) 12' away, leave it out.