Guess what we got today?!
It is an awesome car seat that will work from 5-120 lbs! Perfect for the myriad of placements we are going to get. It also is 17.3 inches across, according to several Prius boards it should fit 3 across in the back seat.
You can look up more information about this amazing car seat and purchase it here,
We are looking at another car seat as well for if we get younger placements. (This will add ease of carrying them, since the Diono does not carry children outside of the car). This Chicco is 17 inches across so it will mix and match arrangements with Diono's perfectly in our Prius.