Driving encompasses several issues: Physical ability, legal permission, safety, the importance of independence. You will likely be able to drive safely and legally for several years, depending on your age and general physical condition. However, Parkinson's disease eventually affects reaction time, ability to handle multiple tasks, vision and judgment.
A good way to gauge whether you should be behind the wheel is to ask yourself: If a loved one were my passenger, would I be risking that person's safety because of my Parkinson's disease? Also, be aware of others' reactions. If your spouse or child has commented negatively on your driving ability, or is visibly reluctant to be your passenger, check your ego at the door and carefully consider their concerns.