Many credit cards actually offer a rental car insurance policy to cover you while you have a rental car. This is most common with travel rewards credit cards, but many regular credit card companies have extended the program beyond the travel rewards cards and offer it with all their cards.
In addition to just covering the basics if you are in a wreck, many of them have a full replacement value for the rental car company of up to $50,000. That means even if the car was totaled, you would likely have the coverage you need to pay for the damages without going broke. This also should kick in if the car were to be lost or stolen.
Many of the best credit cards these days also offer a little more for your money. They have 24/7 roadside assistance policies. This means if you are in your rental car in a strange town, and you break down, have a flat tire, or some other similar problem, they will come to your rescue and get you back where you need to be.
Not all cards have these services. If you are in the market for a new credit card, you should do you research to see that the one you get is the best credit card deal around and will give you a few of the extras you deserve.