I can't think of any other car that you don't even have to say the whole name for people to know exactly what you are talking about.
That may very well be every 49-51 Mercury picture I have in digital format other than this one:
which I had to include.
I can remember sitting with my Grandfather watching American Graffiti on Starcase (that weirdo precursor to cable).
When this thing caught my eye I know I asked what it was, to which he responded "The Merc."