The mystery of circular objects?

I have just noticed something when I turned on my TV this morning. On the History Channel, they were showing UFO mystery. Now, I do not know whether or not the story of UFO is a hoax, but one thing that i'm confused about -- their circular spaceships. Shortly after the program was over, I did some reasearch in planetary movements and our planets' shapes. It came out that the circular shapes gave them maximum rotation. When you're driving a car, you can never turn a corner without moving an inch from the original position. But, with a circular object, you can turn at a single point in space. What is so special about the circular shape according to you? I would love to hear your opinions.