I read once that they wanted Autobahn to be longer but sadly the limitations of the LP was 23 minutes. If only they had access to the CD! What could have been.
Still as it was it must have been a tremendous shock to the hippies of the era. It was the sound of the future.
Honest question, why a shock to the hippies? In 69 less than a decade before there was Woodstock and the music, while not futuristic, was very progressive and innovative. All in all I think these folks might have had more to do with the hippies than anyone else at the time, specially in a time right after the world war, with the extreme anti-fascist sentiment in the country.