This article is from the Blues Brothers FAQ, by Glen Pringle email@example.com with numerous contributions by others.
1974 Dodge Monaco sedan.
From the photo in the Blues Brothers Private book, the original
Bluesmobile (which was traded for a microphone) was a black,
four door '68 Cadillac Fleetwood. The right front fender was
damaged and held on with tape. However, in the novel of the
movie, it's a "battered blue '58 Cadillac with mantra-ray fins".