Re: 3 kids
If you like the IS you might want to look at the new 3 series. Its a little bigger, especially in the rear while still being small and sporty. The IS will be totally refreshed this year too, and all new for 2013 most likely.
My main concern with the IS would be the rear facing seat, once he's out of that it might be okay...
2011 Jeep Grand Cherokee Laredo X. Natural Green Pearl w/ Black interior. QT1, moonroof, 430N, trailer tow.
2013 Lexus GS350