In today's 1Q conference call, Elon stated that Model Y will not use a CAN bus, and instead use a new high speed bus. He said that while Model S used 3 km of wiring, and the Model 3 uses 1.5 km of wiring, the Model Y will use 100m.
He also said they will finally discard the legacy 12V power, which he derided as saying wasn't the right voltage for anything.