Caveat: This is somewhat debated amoung economic historians.
But a mix of:
* Marshall plan
* Strong institutions (think of paperwork in bureaucracies / rule of law sometimes being very good for growth)
* Strong education system (German universities were world-class pre-wars and good to very good post-wars)
* Luck: That cars became SO significant for rich countries was huge for Germany, the very strong south’s economy is basically lots of car companies + their partners (+ the rest).
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