The 911 can trace its roots back to sketches drawn by Ferdinand "Butzi" Porsche in 1959. The Porsche 911 classic was developed as a much more powerful, larger, more comfortable replacement for the Porsche 356, the company's first model. The new car made its public debut at the 1963 Frankfurt Motor Show (German: Internationale Automobil-Ausstellung). The car presented at the auto show had a non-operational mockup of the 901 engine, receiving a working one in February 1964.
It originally was designated as the "Porsche 901" (901 being its internal project number). 82 cars were built as 901s. However, Peugeot protested on the grounds that in France it had exclusive rights to car names formed by three numbers with a zero in the middle. So, instead of selling the new model with another name in France, Porsche changed the name to 911. Internally, the cars' part numbers carried on the prefix 901 for years. Production began in September 1964, the first 911s reached the US in February 1965 with a price tag of US $6,500.
The earliest edition of the 911 had a 130 PS (96 kW; 128 hp) flat-6 engine, in the "boxer" configuration like the 356, air-cooled and rear-mounted, displaced 1991 cc compared with the 356's four-cylinder, 1600 cc unit. The car had four seats although the rear seats were very small, thus the car is usually called a 2+2 rather than a four-seater (the 356 was also a 2+2). It was mated to a four or five-speed manual "Type 901" transmission. The styling was largely by Ferdinand "Butzi" Porsche, son of Ferdinand "Ferry" Porsche. Erwin Komenda, the leader of the Porsche car body construction department, was also involved in the design.
The 356 came to the end of its production life in 1965, but there was still a market for a 4-cylinder car, particularly in the USA. The Porsche 912, introduced the same year, served as a direct replacement, offering the 356's 4-cylinder, 1600 cc, 90 hp (67 kW) engine inside the 911 bodywork.
Source: Wikipedia, 2012