What they said was that, when they were recording "Autobahn", they were trying to capture a very specific experience of driving on an autobahn in Germany in the 70s and they related that to the way the Beach Boys had captured a certain lifestyle in California in the 60s, they were trying to emulate that. "...in their songs they managed to concentrate a maximum of fundamental ideas. In 100 years from now, when people will want to know what California was like in the 60s, they only had to listen a single by the Beach Boys." So there was a conceptual side to it but, being clever fellows, they also included some musical reference points - so the harmony vocals and, especially the "Fahr'n fahr'n fahr'n" vocal refrain. Nonetheless musically it's absolutely nothing like the Beach Boys, particularly the full 23 minute version. You're dismissive of the fact that it didn't sound like anything else as if that somehow is secondary to... what exactly? Strange chords or chord sequences or time signatures? I don't know what you're looking for. "I Am the Walrus" is just a psychedelic rock song, it's not radical in terms of any of those things either, it's the sound and arrangement and feel of it that make it stand out.