3 car seats in a row.

Okay. So we have a Mazda 3, which isn't the smallest of cars but it defiantly doesn't have much space, especially in the back seat. I already have a 4 year old that's front facing and a rear-facing 1.5 year old. I already know that I'm going to have to buy new car seats my 2 older babies as well as the one in the way. Now, I've decided on the Diono Radian RXT for my two oldest. I really would like to get the new baby an infant car seat instead of a convertible and I've got my eye set on the Maxi Cosi Max 30. Basically my question is does anyone happen to have a Mazda 3 or a car similar in size? If so what seats do you have? Do you think it'd be possible to do a Maxi cosi along with 2 dionos or should I just get 3 Diono's? Tia!!!