I've recently found links for sites that sell excess car rental insurance (AKA super CDW) for much less than what the car rental companies are offering. The policies are separate from the CDW from the rental company and cover the excess (usually around 1000euro) that the CDW doesn't cover. Has anyone had experience with these and can recommend one of the sites?
We have always used, the now infamous, AIG's annual worldwide cover policy. Touchwood, have never had to claim so don't know about their customer service. It seemed to offer the best value and was accepted in Italy and New Zealand.
There are a number of third party companies that offer coverage for rental cars. It can be a good deal for longer rentals where leasing is not a good option, but I would still discuss it with whatever rental agency that you decide to go with, rather than showing up at the counter and dealing with it then. Also, the real question to ask of the insurance company is: If I get in an accident, what is the claim procedure? If it comes down to you are on the hook (your credit card) until we decide to pay...then it may not be a great deal.