This option allows you to add additional drivers to your car insurance policy in the event that you are not the only person that may drive your vehicle. This provides additional protection to your vehicle in the event that your vehicle is involved in a car accident, the additional driver option would provide insurance coverage whether it was you driving the vehicle, an additional driver or any driver that you decided to add to your insurance policy. Check with your insurance company as some are more relaxed about additional drivers while others may not be.