Seidel often entered cars under his own name, or under the Scuderia Colonia banner. After having been refused a start at the 1962 German Grand Prix due to slowness, Seidel got in an argument with officials from the Automobilclub von Deutschland. Combined with some doubts about the level of preparation of his cars, Seidel's competition licence was withdrawn, and he offered his two cars up for sale. In spite of not having a licence, Seidel competed in the non-championship 1962 Mexican Grand Prix a few months later.