My experience with these great cars, have owned 4 grand marquis, a 1996 2003, 2006 and currently a 2010 . The manifold cracked on the 96 ,ford paid for the repair ,sold it to a friend who drove it untill it was stolen ,no more problems with-it untill then .The 2003 and 2006 I sold to same friend both have well over 200,000 miles now , they are his daily drivers ,no major repairs on either .My 2010 is my last ,now has 72000 miles no problems .I base my conclusion on this .I don't think age was a factor, they were constructed of a composite material that did not hold up .