Very interesting indeed, taxiguy! Especially when compared to U.S. recession years.

http://en.wikipedia.org/wiki/List_of_recessions

This explains the significant drops of Ford and Chevrolet production numbers that you've made available:
Chevrolet:
1973 to 1974 minus (-) more than 300,000 units
1979 to 1980 - almost 200,000
1980 to 1981 - more than 160,000
1991 to 1992 - almost 100,000
Ford Crown Victoria:
2001 to 2002 - more than 15,000