I used gemut.com to rent my car in Germany. The process was smooth and their price was good. I highly recommend them.
I'm not in the business of making rental car company recommendations, but I don't have a good feeling about Gemut because they never quote what I request.
Before every trip, I prepare a detailed itinerary and figure the cost of public transport using local point-point, regional, and Saving Fare tickets, and then compare it to using a rail pass or a rental car. For one or two people, public transportation always wins by a big margin. When I compare the cost of a rental car, I often ask Gemut for a quote with complete CDW coverage (I'm comparing apples to apples; I have no collision damage risk with the train, I don't want it with a rental car). Gemut always refuses to quote what I ask for, giving me instead a price using without CDW and telling me to use my credit card's insurance. Having read the fine print, and reading about other travelers bad experiences with counting on their CC insurance, I would never rely on my CC insurance.