carseats in 2004 prius?

No experience with that specific seat, but have used the Britax Boulevard in the Prius. As long as you aren't super tall (over 6') they fit fine rear-facing.

I recommend buying from a local store if possible as any good one will let you test fit the seat before buying it.

 

I've had the Graco infant seats (with base) and now they've graduated to the convertible Cosco seats. Neither have been an issue with my '05. We are, however, fairly short in my family, so the driver's seat doesn't have to go back very far.

 

I haven't had that specific seat either, but we have two car seats in the back of a 2005 Prius and it is fine. On the outboard rear seats you will want to use the LATCH, I would not put the carseat in the middle because the manufacturers, in their infinite wisdom, have not provided for the LATCH there. But it is possible to use the middle with the belt if you choose to do that based on the possibility that it is the safest position. I chose the drivers side of the rear seat because it is the same side I'm on.