My sister is pregnant. She drives an old Saturn SL2, so her back seat is very small. A new car isn't an option right now. This will be her third kid. My niece is out of a booster. My nephew will have just turned four when this baby is born and will probably have to go to a booster. The center position is lap belt only, so the baby will need to go there. What is a decent quality, very narrow, infant seat? (And putting my nephew in a Radian is out of the question.)