Why Was Porsche 901 Changed to 911? – Video
In 1964, 82 cars were built and the 901 was presented in October at the 1964 Paris Auto Salon. There, French car maker Peugeot objected to Porsche using any three digit number where the middle number was 0, asserting ownership of the naming rights in key markets, and having already sold many models with that scheme.
So, Porsche simply replaced the middle 0 with a 1, and called the car Porsche 911. Officially the 901s already constructed were used for testing and for exhibitions, and Porsche sold none to private customers.