I watched A Simple Plan again to see if I could spot director Sam Raimi's 1973 Oldsmobile Delta 88. Crossroads had already asked about it on the page:

http://imcdb.org/movie.php?id=120324

There is only one part of the movie that has a longer American sedan completely in the darkness. As many of you know, Sam Raimi's car is in at least 10 of his films if not almost all of them. I wonder if the snowy weather in the Simple Plan had something to do with it?

This is the suspect car that is very hard to identify: