Multiple versions of this car exist, all based off of a 1959 Cadillac Miller-Meteor ambulance. The original Ectomobile or "Ecto-1" is seen in the first movie. By the second movie the car had been upgraded to the "Ecto-1a" with additions like an even-more crowded roof-rack, a satellite dish and digital announcement boards on either side that would flash advertisements for the ghost-busting business.
The video-game version of the Ectomobile is the "Ecto-1b" which was featured in the 2009 game Ghostbusters for XBox360, PS3, Nintendo Wii, PS2, and Nintendo DS. It retains few details from the Ecto-1a in favor of a look closer to the original Ecto-1. It gains the addition of a "super-slammer" on top of the car that acts as a super-powerful ghost trap.