When I was a kid, my father had a Cadillac limo that belonged to Attorney General John Mitchell, at one point. It was like a 1972 limo, and you could see it in some of the Watergate footage. There are some news clips where he was getting out of the car in front of Capitol Hill and stuff.
Kinda cool, but it's not like that helped the value of the car any. My dad actually bought the car from a funeral home. He got it dirt cheap, drove it for a few months, and then sold it for a profit.