Hearse is in MP, although did it originally come in MP from someone taking one from SP and then they spawned some and people took them and then those people spawned more, etc?
Nope, it can be found in two locations that I'm aware of. It's a rare occurrence but it will spawn. If you are interested in exact locations, just YouTube it.
I managed to grab one the other day.
I've noticed that:
1. If I take it out of my garage, then go in a different car to the church near Del Perro, they will spawn.
2. If I don't take it out of my garage, they won't.
3. If I take it out and then go park it a few blocks away from the church, they won't spawn when I walk over. If I drive it to the church, they do. Between 1-3 spawn.
4. If I take it out, they spawn at the cemetary near Del Perro, but they don't seem to always spawn at some of the other churches/spots where they have been seen.
5. They are the ab-so-lute best car for trolling. There is no better troll mobile.