Siblings Susanne Klatten and Stefan Quandt own almost half of Bayerische Motoren Werke AG. The billionaires are descendants of Guenther Quandt, who built a German industrial empire by, among other things, supplying weapons to the Nazis during World War II. In the years since, the family has established stakes in both Daimler-Benz AG and BMW. Today, Klatten is Germany’s second-richest person, worth $18.6 billion, with interests in chemicals and carbon production, according to the Bloomberg Billionaires Index.