Porsche 911: rear seat belt may not hold child seat high
The rear seat belts have a locking mode you use to hold a child seat tightly in place. On these cars that lock can release too early, so the belt goes slack and the child seat is no longer held firmly against the seat. In a crash, a child seat that can shift around will not protect the child the way it is meant to. The dealer will inspect the rear three-point belts and replace them if needed, at no charge to you.