Porsche named their new sports car the 901 — Peugeot's trademark made it the 911

In 1963, Porsche unveiled its new sports car at the Frankfurt Motor Show. The internal project number was 901, and the first 82 examples carried the 901 nameplate. The car was a successor to the Porsche 356, designed by Ferdinand Alexander Porsche, and featured a rear-mounted flat-six engine that would become the defining sound of the 911 for decades.

But Peugeot, the French automobile manufacturer, had trademarked all three-digit car names with a zero in the middle — 201, 301, 401, 601, and so on. Peugeot had been using this naming convention since 1929 and had registered the trademark in France. Porsche could not sell the 901 in France, the country's largest car market, without infringing the trademark.

Porsche faced a choice: fight the trademark battle, sell the car under a different name in France only, or rename the entire model line. The simplest solution was to change the 0 to 1 — turning 901 into 911. The change was made before the car went on sale in November 1964. Internally, Porsche's part numbers carried the 901 prefix for years, but the nameplate read 911.

The 911 became one of the most iconic sports cars in automotive history. Across seven generations, it sold over a million units and defined the sports car category. The 901 name was forgotten by all but Porsche enthusiasts. What began as a forced name change — a trademark dispute resolved by a single digit — became a brand identity stronger than any marketing department could have designed.