Having been with both German & Japanese auto manufacturing, IMO, the basic answer lies in that the Germans focus on "high tech" gadgetry in many cases while the Nipponese focus much more on reliability across the board.
Simple answer to a complicated situation & many exceptions in both cases.
MM
The above is probably the reason.
The Germans focus on technology (e.g., BMW's iDrive control system that no one could figure out) while the Japanese focus on statistical quality control (W. Edwards Deming system - see
http://en.wikipedia.org/wiki/W._Edwards_Deming). Deming first offered the techniques to US automakers, but was rebuffed; he was invited to Japan and they adopted statistical quality control - the rest is history. The highest industrial award is Japan is the J. Edwards Deming Award.
Also, the German cars are not so unreliable, but when they break down, they are expensive to fix.
