The Ecto-1b was a updated version of the Ecto-1 used in Ghostbusters: The Video Game. The vehicle looks to be a cross between the Ecto-1 and the Ecto-1a.
Super Slammer Muon Trap
Larger and faster than portable containment units, this vehicle-mounted, high-expansion, rapid-cycle trap is capable of capturing ghost instantaneously.
A Close up look at the Ecto-1b license plate
Conflict
While the Ecto-1b is clearly named that in the PC,PS3, and Xbox 360 versions; its however referred to the Ecto-1 in the Wii version. Is it canon, and does that mean the Wii and other versions like it are not canon?
THis can be rectified by saying that Ecto-1 could simply be just a nickname or a contraction of Ecto-1B.