Renting a car can be a daunting and confusing experience. The contract is lengthy, and few customers take the time to read it in full, particularly when they are standing in line at the counter with impatient people behind them. Customers who are in a hurry to get their car and leave will often agree to whatever the agent recommends, often with expensive results.
Purchasing additional insurance when you rent a car may or may not duplicate coverage you already have. The coverage included by many rental agencies may include one or more of the following:
Collision damage waiver - Should you be involved in an accident, this coverage transfers liability for the damage from you to the rental car company. This coverage tends to be rather expensive, and can cost up to $20 daily. Your credit card may cover you for this; you should check with your credit card company before you rent the car just to be sure.
Liability insurance - This covers damage to other cars or individuals should you be involved in an accident. This coverage almost certainly duplicates coverage that you may have under your own auto insurance policy. You should contact your insurance company to be sure you will be covered for liability in the event of an accident.
Personal accident insurance would cover health expenses for the driver and passengers in the event of an accident. This is also a likely duplication of coverage from your personal auto insurance policy.
Loss of personal items from the car due to theft may or may not be covered under your own auto policy. You should check with your agent to see if your suitcases, golf clubs, or whatever are covered against potential loss. You may purchase such coverage at the time of rental with most companies.
If you simply decide that you want to be covered for everything, you could easily be paying $50 per day or more for the sum of all coverage listed above. Given that $50 a day could also purchase a tank of gas, it really isn't a good idea to reflexively purchase any and all insurance offered by the agent. A smarter idea would be to take a few minutes to call your insurance agent and your credit card company a few days before you plan to travel. Simply explain that you plan to rent a car for a trip and you would like to know what, if any, coverage is available to you as one of their customers. You may discover that you are already covered for a number of potential problems. If it turns out that you are not already covered, then you can purchase needed protection when you rent the car.