Definition: Insurance Day Car: A day when all major insurance companies offer a special discount on their premiums. This can be as low as 10% off for most policies, but it may vary by company. Insurance Day Car usually refers to a marketing campaign or event that highlights the benefits of using a specific product or service during this period. The idea behind an insurance day car is to encourage customers to purchase policies from a particular insurance company and use them in everyday life, which can ultimately lead to reduced premiums over time.