This movie is quite obscure, (and old, probably 70´s or 80´s) all I really remember is the end; someone goes "back" to the crashed car in the ditch, and the dead body comes alive. The person panics for some reason and starts shooting the "dead body", who won´t die, but instead takes of the mask he or she is wearing and reveals him/herself to be a totally different (alive) person. Really nightmarish, that´s all I remember...