Everyone:
I'm worried that what has been written so far in this discussion is going to cause a lot of confusion, and to avoid that, I would like to clarify a few things:
1) The "Green Card" system - as Antyx pointed out, many, many countries participate in the
Green Card' documentation system, but this should not be interpreted to mean that if you have a 'Green Card', your insurance is valid for all the participating countries.
The Green Card system is
primarily a document standardization protocol that is intended to ensure that authorities such as police, etc. in one country can easily comprehend that a vehicle from another country has adequate insurance for a different country.
It is entirely up to the insurance company that is issuing the insurance policy to decide how many (or how few) different countries they want to extend their insurance coverage to. For example, an insurance provider in any one of the Green Card participating countries might choose to insure a vehicle in only one specific country - for example, a French vehicle that is insured only within France. In such a case, the insurance company could issue a Green Card, but all the boxes would be crossed out except for the box 'F' (for France).
Perhaps this might be done because the customer wants a lower insurance premium, or perhaps this might be done because the insurance company doesn't want the risk associated with insuring the vehicle in other countries.
At the opposite end of the scale, it is possible to get a Green Card that has just about every possible participating country covered. This is uncommon, and the only example of this I have ever seen was issued by a Russian insurance company.
The 'most common' scenario for a Green Card is that all of the full member EU countries are covered, plus Switzerland. But, even though this is the 'most common' scenario, it is by no means an obligatory scenario.
2) A Single Country Insurance Document - if you purchase insurance that is only valid in one specific country, the insurance provider might elect to provide you with a unique country-specific document, instead of a Green Card format document with only one country box checked. This is a non-standardized document, but it is known, recognized, and accepted by authorities in the one specific country that issued it.
If you want to see examples of this, look at this post that I made several years ago showing a bunch of single-country documents from the Balkan area:
Balkans Insurance - Here's the story, with details & sample documents
Then again, the insurance company, if they are so inclined, might also elect to provide you with a 'Green Card' with all the boxes crossed out except for the one country where you bought the insurance. The effect and coverage would be identical.
3) To Sum Up - Having a 'Green Card' insurance document does not guarantee that you have insurance coverage in any particular group of countries. You will only be insured in the countries whose boxes are not crossed out... and it's up to you and your insurer to decide upon how many countries you want to have coverage for.
It is
very common for insurers to decide that they are simply not going to insure vehicles for operation in certain countries, which means that even though Lower Slobbovia might be a participant in the Green Card document standardization scheme, no insurance company in the world outside of Lower Slobbovia will sell you insurance to operate your vehicle in Lower Slobbovia.
Michael