How much does one have to pay to go the whole way from San Sebastián (Northern Spain) to Munich (Germany) via French (and possibly Swiss) highways (i.e. autoroute or Autobahn)?
Google Maps currently suggests two routes. One goes through France via Stuttgart and the other one goes through France and Switzerland via Bern. Which of these options is currently the cheaper one in terms of road user charges?
Anything not going through Switzerland will be much cheaper.
Switzerland sells annual toll tickets ('Märkli') only, which for a single trip easily beats any other toll.
Each countries' toll road agencies will have websites where you can calculate the expected amounts. Note that in some countries, different toll roads are handled by different agencies.
@Aganju's answer is spot but here is another more generic tip: Use viamichelin.com or mappy (as suggested by @Olielo). They do not seem better or worse than Google Maps to find a route, but they also provide an estimate of the tolls that seems pretty accurate (roughly matches my experience, even if I haven't done any systematic comparison).
When looking at these nunmbers, you have to beware that some countries (France, Italy) have tolls you have to pay every time you use a given section of motorway and others (Switzerland, Austria and many other countries in Central Europe) have yearly or monthly stamps or "vignettes" covering the whole network. That's important if you are contemplating other trips or even merely coming back by road as the return will cost you exactly the same price if you go through France but will be free (or already paid for if you will) if you go through Switzerland.
