Here's how you can do it with the new Honda Fit by folding up the rear seat bottoms to create a large center cargo area:
I like that Honda Fit. Pretty slick stuff.
I just bought a couple of Toyota/Scion xBs. Similar idea, but boxier.
Small, tall, and roomy.
Forget the dog food... put down a nice fluffy pillow, and that's the dog's bed.