It's also a crime to insult people outside of cars in germany. When doing so behind the steering wheel it may result in a temporary driving ban in addition to a penalty.

IANAL, but in the German legal system, one can only be convicted on an insult charge if the insulted party explicitly requests it.

Behind the steering wheel, the situation is different because road rage will usually not be litigated as an insult, but as attempted coercion.