Why do people back up into parking spaces?
Answer by Ben Reimers:
It’s much easier to reverse into a car space where room is limited than it is to drive straight in.
The reason for this is that the back wheels are fixed in direction in relation to the car. This effectively makes the pivot point of the car the middle of the rear axle. In turn, this means the rear wheels don’t follow the same path as the front wheels, they will cut the corner. When space is limited, your turning circle may not be small enough to get into a tight space, forcing you to make a couple of gos to get in, straight.
See how the car is crossing the lines on either side? You rarely have the room in a parking lot to be able to manoeuvre your car to be driving directly into the space, you have to straighten up inside the space itself. Not easy to do with the pivot at the back of the car, often causing people to reverse half out of the spot just to be straight (holding up traffic again and confusing people into thinking you might be leaving, when you’re not).
But if you reverse in, you are placing your pivot point in a position where you can more easily get into the car space perfectly the first time.
Because some people were questioning the way the car in the first image crosses the line I have put together this quick animation that shows how the rear wheels move towards where the front ones are and “cut” the corner … by up to half the width of the car! I used inverse-kinematics to get the motion so it’s not just my interpretation of what will happen.
The following is based on an average sedan length of 5 metres and an average turning circle of 11.75 metres. The outer circle is the curb-to-curb turning circle, the inner circle is the width of the car and there to illustrate my point about how the rear of the car.
Or as a GIF:
See how the car is positioned when it gets to the horizontal line: almost at a 45 degree angle. It takes another whole length to get straight again.