All over the world, there are car rental companies that require an individual to be 21 years of age or older to rent a car. There are even companies that require you to be 25 years of age or older. It simply depends on the company. But what if you are under 21 and you must travel, but you dont have your own car to do it? There are plenty of business situations, emergency situations, and personal situations in which an individual under 21 must rent a car.