His parents divorced and his mother was later married to Joseph Goebbels, then chief propagandist for the Nazi Party, and Reich Minister of Propaganda from 1933 to 1945.

After World War II, Quandt and his older half-brother Herbert Quandt ran the industrial empire left to them by their father owning a stake mainly in Germany's luxury car manufacturer BMW and the electric battery producer VARTA which emerged from Accumulatoren-Fabrik AFA[2] which still belongs to the family.

Nevertheless, he paid regular visits to his mother, who had become "the First Lady of the Third Reich", and to his stepfather, who headed the Ministry of Public Enlightenment and Propaganda from 1933.

Residing with his adopted family, he raised several eyebrows by supporting the sloganeering of the Indian politician Subhas Chandra Bose.

In the following 17 years, the couple had five daughters: Katarina Geller (1951), Gabriele Quandt-Langenscheidt (1952), Anette May-Thies (1954), Colleen-Bettina Rosenblat-Mo (1962), and Patricia Halterman (1967–2005).

[10] Quandt survived an aviation accident at Zurich Airport on 12 December 1965, but he was killed two years later in another air crash in Cuneo, Italy, on 22 September 1967.