+1
I keep a business UMPE card just for car rentals, it's the only thing I use it for (which is thousands a year.)
Why a business one? If you're using it for business rentals, the ink is a better all around card.
I like the amex premium coverage because it's supposed to cover full sized SUVs too. I have yet to total a suburban, so I haven't tested it out yet. Citi should also, I think, but it's supplementary insurance.