Are the dimensions of the suitcases ~ 4.75" x 5.5" x 2.25"?
I have a metal lunchbox (Curious George) this size and it looks about the same in comparison. Mine is all sun faded from sitting in the window.
We got the pink car seat at the BAB store. It fits well in the recess in the back seat where the arm rest is when not laying down. Doesn't strap in, but wedges quite nicely.