Have you ever witnessed the 1959 Cadillac Miller-Meteor limo-style endloader combination car (ambulance conversion) [thank you Wikipedia article!] that is the Ecto-1, better known as the Ectomobile?
But I read a blog that has people going to E3 (last year) who have seen it, and have taken some photos of it. Seems to be the real deal. Read the full short article here and see the photos here.
Oh, how I love the Ghostbusters and their method of transportation!