I use the United Explorer card for my car rentals because coverage is primary not secondary
Decline the rental company’s collision insurance and charge the entire rental cost to your United Explorer Card. Coverage is primary and provides reimbursement up to the actual cash value of the vehicle for theft and collision damage for most rental cars in the U.S. and abroad
My other card (Jetblue plus Mastercard) has secondary coverage in the USA and primary coverage outside the USA
As mentioned neither provides liability coverage
