After making their initial appearance on the hospital steps and answering a few questions from local media, the royal family returned into the hospital to get their little prince strapped into his car seat. Will and Kate's pick? Britax's Baby-Safe Plus SHR II ($200). While this specific model isn't currently available in the US, you can shop similar seats at the brand's website.
Editor's Note: While the royal family can do as they please, your new baby shouldn't be swaddled when he's strapped into his car seat!