回复：租车问题

Call your card's customer service or check their website. For mastercard (platinum): It
does not cover you for damage to someone else’s vehicle or property, your property, or personal property inside the vehicle. It does not cover
you for any injury to any party.

I think this means you can only use the policy to cover the rental vehicle and you will be responsible for damage to other parties in case of accident that you are responsible for.
So having your own liability insurance is always a good idea.