1) An insurance policy is not confidential: your employer's excuse makes not sense.2) Their auto policy will most likely not cover your parent's car (it's registered to them, so legally it's their car) in any event, and if they won't show it to you, assume you are not covered.3) If you get into an accident while driving for work, or a patient is injured in your parent's car, you and your parent's may well be liable.4) If there is an accident or injury, your parent's insurance will most likely not cover it, unless you disclose to the insurer in advance that you use the car for work and buy the appropriate insurance. A non-work auto insurance policy does not cover work use of cars in most instances.