I've been given an orange Dodge Nitro before. Most of the cars I've been given have been white, so much so I call the color "rental car white" and is the only color I exclude when looking for cars to purchase.
But yes, we can choose the category. And you will get it unless they are out of cars for that category. An orange Dodge Nitro was considered an "upgrade" from what I reserved. One time though I had reserved a Camry and they were out so they upgraded me to a Prius instead. It was nice driving the car back to the airport after a week of driving and not having to fill up the gas tank all week.
But yes, we can choose the category. And you will get it unless they are out of cars for that category. An orange Dodge Nitro was considered an "upgrade" from what I reserved. One time though I had reserved a Camry and they were out so they upgraded me to a Prius instead. It was nice driving the car back to the airport after a week of driving and not having to fill up the gas tank all week.