I own a 2013 Lincoln Mks. The engine cover is made out of a black foam material. My 2008 and 2013 Lincoln Mkz's both had the black hard plastic covers over the engines. This foam cover is very flimsy and is not of the same quality as the hard plastic version. Both holes where the fasteners attach it to the engine cracked causing the cover to become loose. I took it back to the dealership and it was NOT covered under the bumper to bumper warranty. So I used some Dr. Bond super glue and carefully glued the crack together and then used a black plastic spray can lid and cut out 2 pieces to to fill in the whole area where the fasteners go through the foam and super glued them to the foam. It looks great and added stability to those areas. My vehicle was purchased a year ago and I have only put 4,000 miles on it. I have never removed that cover and with the low miles, I don't think anyone else had either.
PS. Not only did the upper engine cover fail, the lower engine cover is also flimsy. There are 4 holes that have a fastener through them to attach it to the vehicle frame. The front left hole blew out, so the dealership attached it to the vehicle frame with a black plastic tie strap. I took it back to the dealership and SURPRISE, not covered under the bumper to bumper warranty. So I took 2 thick round black plastic fender fasteners that were the same diameter and drilled a hole through them and Dr. Bonded them to the blown out hole on each side of the cover. Now the fasteners will keep the lower cover tightly attached to the frame and it is a first class quality repair. A new lower panel cover is almost $200.00 OEM.