Sure you can choose your category. There's just no relying on it coming true when you arrive at the counter. them-> "Here are the keys to your Dodge Durango"

Sure you can choose your category. There's just no relying on it coming true when you arrive at the counter. them-> "Here are the keys to your Dodge Durango" you-> "no, actually I reserved a 4-door sedan" them-> "I know sir but we don't have any left" you-> "huh? I reserved one. what does a reservation mean?" them-> "it's subject to availability sir" In other words, (like many restaurants, like many airlines, hotels, etc), you can "reserve" anything you like, it doesn't mean it has been set aside for you. welcome to the nuthouse