It's unlikely that three standard car seats will comfortably fit in the backseat of a Chevy Impala. While the Impala has a spacious backseat, three car seats, especially if they're larger models or include booster seats, will likely be a tight squeeze.
You should definitely try it out with your specific car seats in your specific Impala before relying on it for transportation. The size and type of car seat (infant carrier, convertible, booster) greatly impacts how much space they take up.
