Oh wow. I had to chew on that one for a while. Well played.

This joke died of dysentery. (Well done)

It works on a few levels... try to cross a stream in a Ford and it'll stall and break down in the middle of the steam

I think it would work a smidge better without the “a”.

Why did the Ghostbusters use a General Motors ambulance for ECTO1 instead of Ford?

Because they didn't want to cross streams.