rental insurance through credit card

My suggestion is to call the credit card company's insurance division and go over your trip with them. I rent quite a bit and AMEX recently changed their rules without alerting me. I was actually driving without coverage unitl I checked about some potential damage to the car.

The wording on this change was so bad it took me a few minutes to understand the change because it was so hidden.

You can Google the name of your credit card and lookup terms and conditions online. There will be a section on rental car insurance.
Very often, the rental car coverage is secondary to your home comp/collision insurance policy. You would have to carry a copy of your home insurance policy too--if that is the case.
Note that the rental car company also has the capability of charging your credit card for damages--almost like the card is additional collateral if your limit is high.

Very often, the rental car coverage is secondary to your home comp/collision insurance policy.

That's actually not true outside the US. When I've used credit card insurance in France, the policy terms always said that it was secondary in the US but primary outside the US.
As to what you need to show, for a couple of decades when we rented in France and used cc insurance, I would just tell the agent when I picked up the car that I was relying on cc insurance, and he/she would say "That's fine." But car rental companies may be getting stricter with this, so at the very least you should have a copy of the terms and conditions. You can usually get this from your credit card company's web site, or maybe you've kept it in a file when you got the card.

If that is what you are relying on know the terms and coverages cold. I don't hesitate to decline coverage in the US as both my auto insurance and my Visa card provide coverage. But, overseas I probably overinsure, not wanting to struggle to have my credit card cover a claim. So, I either buy it as part of my comprehensive travel insurance (you are getting that, right?) or buy it through the agency.

We just rented a car this past June in England from Europcar and I used my CC insurance as primary coverage. I also bought a very low-cost insurance from Europcar to cover injury or damages to other people or their stuff for peace of mind. These were sufficient. And had I declined to purchase anything from them in the way of insurance that would have been fine too. I did not carry proof with me. I did lots of research of what my different CC's offered me before booking my car so do your research and then you'll have to weigh the cost to benefits should something happen. Luckily for us nothing did and I was happy with what I paid.

I have researched my credit card, actually got out a magnifying glass and read the fine print, then got smart and pulled the same guidelines up on the computer...duh!!! I printed out the rental insurance info from the credit card Guide to Benefits and I am calling Monday to get an official Letter of Coverage.

I am also calling my vehicle insurance, State Farm, to find out if they cover rentals, which I believe they do (within the US), depending on the state you live. If they do not offer international coverage on my regular policy I am going to ask about UNOC, Unlimited Non Owned Car Coverage to see if that applies.

Someone previously had mentioned something about homeowners insurance, I believe, and I couldn't see why that would cover a vehicle not on my property but I checked all the same. Nope....
Hope I am not overthinking this. I just don't want to get home and have an astronomical extra charge on my credit card!!

Having a satisfactory report about credit card auto insurance when no claim was filed is like a raincoat review that never saw rain. Look to see what happens with a claim, especially first hand reviews. Be prepared to have your credit card charged for a damages (hope you have a high limit) and then having to seek payment from the credit card insurance.

I rented a car a few years ago in Croatia and used my Amex card, assuming I was covered for damages because I had also opted in to the "premium rental car coverage." Unfortunately, when there was in fact some damage, Amex Assurance (their insurance company) was not enthusiastic about following up on my claim and seems to have done the absolute minimum to contact the Croatian car company...which never responded to them. So they never reimbursed me for the damages as they were supposed to, even though I provided everything they asked for in the claim.

I used to use Amex for everything; now I still have the card but haven't used it in about two years. And I learned not to trust credit card insurance for rental cars, at least not without caveats. I think the mistake I made was accepting responsibility for the damages at the time; I should have simply declined to do that and let the car company hold my deposit against damages, then dispute the charge with Amex. I had even called ahead of time to ask them how I should handle this sort of thing and was told just to go ahead and accept responsibility then file a claim. Mistake! Once I signed for responsibility, the car company lost any incentive to cooperate with Amex Assurance, and of course the fewer claims Amex Assurance pays out, the more profit they make, right?

Had I disputed the charge, then the car company would have had the incentive to provide documentation to prove the damage - all documentation that I would have needed for the claim with Amex Assurance.

Once you determine that your credit card covers you in Germany, ask the rental company what 'proof' they need.

They may not ask as as they have you credit card info they could charge any damage on the car to your card.

The is contract law and, of course, it varies from country to country. To keep it simply -- if I sign a contract (pay a premium) to a third party insurance company (credit card, special policy, etc.) The contract is between the two of us. The car rental company has a contract with me and not my insurance company. Since there is no contractual relationship between the car rental company and my insurance company, there is no reason other than being a nice guy for the rental company to cooperate with or supply information to my insurance. It is my responsible to satisfy my insurance company -- no one else.

...Once I signed for responsibility, the car company lost any incentive to cooperate with Amex Assurance...... The car company never had an incentive to cooperate with Amex Assurance other than good corporate policy. They do not have to and that is the problem with using third party insurers especially in Europe. In the US, everyone is on the same, legal level, English speaking playing field but Europe it can be very different. Everyone tends to think that with third party insurance, you can just walk away and the insurance company will take care of it. Sometimes they do and sometimes they don't.

After our friend wedged a rental car between two stone walls in Italy, it was a relief to simply hand over the keys because our friend opted for zero deductible. Prior to the trip we debated on the credit card insurance or the zero deductible, and decided zero deductible. Whew!

Understanding coverage is one thing, both will they cover you in the country you are renting and any Countries you are travelling in (for example, many CC policies do not cover rental in Ireland and Italy). The other thing though is to understand what the claims procedure is. As was alluded to before, basically it is usually the rental company charges the card, then you work with the CC company to resolve. So you need to understand what information to gather yourself (police report, damage estimate, rental details, etc.) and then who you need to contact to initiate the claim.

Myself, while I will use it on occasion, default CC coverage included in your no fee credit card is about worth what you pay for it. I have higher regard for Premium coverage that costs you something, or included with a higher tier card, but if I have any concern, I, like others, will opt for a zero deductible CDW from the rental company. That is truly the easiest, worry free, solution.

Frank:

"...Once I signed for responsibility, the car company lost any incentive to cooperate with Amex Assurance......" The car company never had an incentive to cooperate with Amex Assurance other than good corporate policy. They do not have to and that is the problem with using third party insurers especially in Europe. In the US, everyone is on the same, legal level, English speaking playing field but Europe it can be very different. Everyone tends to think that with third party insurance, you can just walk away and the insurance company will take care of it. Sometimes they do and sometimes they don't.

That's the point I was making: I took away any incentive the car company had to cooperate when I signed over responsibility.

If I HADN'T signed and let them claim damages against my deposit? Then I would have disputed the charge with Amex. NOW they have an incentive to cooperate - they have to prove damages: receipts, pictures of the damage, etc. That's all the info I needed for the insurance claim. If they don't respond to the dispute inquiry - they lose the dispute and don't get to keep my deposit.