It would be nice for BeamNG to have a map with an autobahn. It would also make more sense as in the 0.25 update BeamNG got a new car with a variant for the autobahn. In my opinion Germany would be the best country to base the Autobahn map of as it is the country with an autobahn which has no speed limit.
Its not exactly what you are asking for but its decent https://www.beamng.com/resources/ssrb.523/ If you want curves look into any of the mod maps based off of Random american flyover states