If anyone is curious, 3 40 breeders fit inside a Nissan Cube I think a few employees at Petco were upset that I got them to unload a pallet so I could buy all of the tanks.
If you take the back seat out you could probably do taller tanks. I stacked 2 in the backseat and 1 rode shotgun. We have taken the backward out to transport a troop of Great Danes and there was a ton of room back there!