Baby car seats??

If you can keep your four year old in a car seat then I admire you first off. Second off, make sure you double check the law, many states say 8 years old or somewhere around 80lbs. Some states could be a lot less. If your 4yr old is close to 5 then when you deliver another child, he/she will be close to 6yrs old and the proper weight to be "legal" to sit in a regular seat and seatbelt giving you that extra space for a car seat! I hope that helps.