Yes, you certainly can. However, there is generally an added cost, and they are only available on a first-come, first-serve basis. Because of this, make sure you reserve the car seat ahead of time. You are at the mercy of whatever type of car seat they provide, and it may not be up to your personal standards or what your toddler is used to. It will also be a car seat that has been used by others. So, while you CAN rent from popular rental car agencies when you’re reserving a car, I highly suggest bringing your own along with you, instead.