He was a co-founder of De Dion-Bouton, the world's largest automobile manufacturer for a time, as well as the French sports newspaper L'Équipe.

[2] Comte de Dion entered one in an 1887 trial, "Europe's first motoring competition",[2] the brainchild of M. Paul Faussier of cycling magazine Le Vélocipède Illustré.

The de Dion tube (or 'dead axle') was actually invented by steam advocate Trépardoux, just before he resigned because the company was turning to internal combustion.

Historian Eugen Weber described an 1899 conflagration at the Auteuil horse-race course in Paris as "an absurd political shindig" when, among other events, de Dion struck the President of France, Émile Loubet, on the head with a walking stick.

De Dion and Michelin were also concerned with Le Vélo – which reported more than cycling – because its financial backer was one of their commercial rivals, the Darracq company.

After a legally enforced change of name to L'Auto, it in turn created the Tour de France race in 1903 to boost falling circulation.

His wealth allowed him to indulge his whims, which also included refounding Le Nain jaune (The Yellow Gnome), a fortnightly publication which "answers no particular need.