If you own another vehicle and it is insured or if you are renting with a large number of credit cards, the answer is nothing. You are much better off declining the LDW and CDW charges, which can often be more than the cost of the rental car itself. That is unless you have no personal insurance or are not paying with a credit card.
Your personal car insurance will cover the damages to a rental car when you are driving it. Most policies include this feature.
In addition, most major credit cards offer coverage as well. It’s supplemental to your personal auto insurance (i.e. the insurance pays first) and will cover the deductible. There are rules of what you need to do in order to get this coverage so read that before you use it.
I speak from (recent) experience on the topic. I rented a car to drive my son to college, it had more room in it. On the way home I backed into another car at a gas station doing about $450 in damage to the vehicle.
Since my auto insurance deductible is $500, that didn’t work for me so I had to go to the credit card. After a couple of weeks of chasing down the paperwork for the claim, it was paid and I was $0 out of pocket. (this just completed about three weeks ago)
Author: Bill Jackson, geek, car nut and political junkie