The guide lines help you see if your vehicle will fit in a parking space or other width-restricted area. Once you have set-up the guide lines using a space that you know your vehicle will fit in, you can use the guide lines to check the size of other spaces.
Setting up the vehicle width guide lines
Open the camera app.
Position your vehicle in front of a space that you know your vehicle will fit in to. Make sure that your vehicle is in line with the centre of the space.
Position your vehicle in front of a parking space. Use the guide lines to see if your vehicle can fit in the parking space. If the guide lines fit inside the parking lines then your vehicle will probably fit in the parking space.
Important: While reversing, also be aware of other obstructions, for example adjacent vehicles or overhead obstacles.