(as in geriatric, I'm afraid). The only -car- with that many seatbelts is going to be one with a front bench seat.
These are going to be at least full-sized, most likely from GM or Chevy. One thing to be aware of, if you are using a carseat for a child, is that many of these cars have their rear seat belts mounted forward of the bight, which often means it's nearly impossible to tightly secure a childseat.
Otherwise, you'll need a vehicle with two rows of rear seats, such as a large SUV or a mini-van.