Almost everyone has 百金卡, unless new students. Check your other card, some may have better benefit for car rental.

I think there is nothing called 抵押 ba? Just use it to pay for it.

"涨我的点数", what is that? You mean APR?

It should have nothing to do with 信用记录. Credit hisotry is for credit, not for car accident.

But one thing is sure: at the time of rental, you must declare that there will be 4 drivers, and all 4 drivers must be listed on the rental agreement. Of course, this will cost you more for the rental fee. Also, you can buy the insurance from the car rental company at the time of car rental. Because your credit card's car rental insurance is very likely to be "secondary" only.

If you are unsure, then I suggest you do the above two, just for safe. Thought it will cost you more. I think everyone will agree that, just do not try to save money on insurance.

Good luck.