For reference: a Prius C, the hatchback, will just fit three small animal Kong carriers.
Haha! I bought a car a few weeks ago, and while it won't likely fit Hooch, our big Mastiff, with any comfort, it's a bunny-sized car. Here they are on the way back from the vet after being spayed and neutered (we have two females and a male). They were pretty popular at the vet's office! So far the females seem to coexist peacefully but the male is still fairly aggressive. We're working on his manners around the gentle fluffy girl and the constantly-terrified brown girl. We're in the process of building them a sizeable outdoor hutch, and the male has a separating wall- it's removable, though, in case things change.