I fit my two boys, one 1 year 8 months and the other 7 months, with a few compromises.
Here's my breakdown
Rear-facing baby seat = Place behind passenger seat. Will leave NO leg room for people up front.
Forward-facing = no issues.
Booster-seat w/ back support = My son constantly kicking my seat back. I am waiting patiently for him to grow a bit older and understand why not to do that!
Booster-seat, no back support = No issues.
I think I will start to have issues, as already stated, once they are teenagers.
Hopefully, by then, they will be mature enough to sit up front and DRIVE the car
This is currently my ONLY car for my wife, and 2 kids, (getting highlander soon!) but it's a very comfortable car, as tight as it may be!