it’s already insured.
That isn’t true.
After an accident isn’t the time to find out what is covered, and what isn’t. It depends on your policy, and what state you are in.
In some cases, your insurance may only cover you if your covered car is in a certified repair shop. In others, (most actually) they may only cover you for damages up to the value of your covered car, not the rental car. If you go cut-rate, I assure you that will be the case. I’ve seen it way to many times.
In addition, few insurance policies cover the loss of revenue to the rental company, they will come after you for that.
I pay for a specific rider on rental cars, since I travel so much, and that even has limits ($65,000 max value covered.)
see post 37