I will be driving from France through Germany to Denmark, Sweden, etc. Is there any type of sticker, pass, etc. that I must buy to go through Germany?
The autobahns in Germany are freeno stickers or pass is required. When driving on the autobahns in France, however, there are tolls. When driving the autobahns, make sure you stay in the right lane. Only use the left lane for passing and make sure you pass quickly. Keep an eye on your rear view mirror. As you pass, you most likely will have a Mercedes on your tail.
Cars in many towns and cities require an environmental sticker. Autobahns don't need one. Usually the outskirts are ok too, its just when going towards the middle of the cities. I would expect if you tell your rental gang where you will be going they may be able to give you a car which already has an unweltplakette on the windscreen.