Having 3 children to fit in the backseat of a Nissan is tough.  We have to consider many factors in choosing a seat--the size of it, the safety of it, and the cost.  My in-laws first purchased a Cosco Scenera to have as an extra seat in their carfor my daughter, who is almost four.  It is a sturdy seat, my daughter likes it because it is high enough that she can see outside the window, and I love that it has the LATCH (Lower Anchors and Tethers for CHildren) system, which I had never seen on other carseats.  Now, as I'm replacing older seats my children have used, I bought a Scenera for my...