is an excellent black comedy from 1971, in which a rich kid obsessed with death gets a brand new Jaguar XK-E in exchange for his Cadillac hearse, which his mother decided to junk in the name of humanity. You can guess what Harold does next.
Unfortunately, the 1965 original was at the end of the movie, and somehow, nobody decided to revisit the idea until 2012. Unsurprisingly, what took Harold two movie days turned into a four year project in real life, starting with Ken Roberts spending a fortune figuring out what car they took the roof from to make the original hearse.
Turns out, the donor was some sort of a Japanese import, which they managed to hunt down, turning the XK-E into a hearse just like the movie's crew did back in 1970. Today, the world's only (known) Harold and Maude Jaguar resides in California.