I'm not sure how they work in US, but I'd try whatever car seat you are getting as not all car seats will fit in all cars so it'll be best to try, if possible, before buying as some places are very fussy with returning car seats.
IS there a list of car seats on the car manufacturers website as to which car seats fit at all?
If you're planning on being able to move baby easily out of car onto buggy then an infant carrier is great, but there are car seats that are suitable from birth to about 4-6 years old which are similar price but last longer, so might be better value, but then these can't be moved out of the car onto pushchair at all so you'll have to keep waking baby to take in and out of carseat