In 1964 Pontiac unveiled their newest concept car, which they dubbed the Banshee. During its development it was called the XP-833 project. This car was a small two-seater with a long, sweeping hood and a short rear deck. Several different versions were constructed, but only two drivable prototypes were ever built. One was a silver hard-top with a straight six engine and the other is a white convertible with a V-8. Both survive today and are in the hands of private collectors.
The styling on these cars is highly reminiscent of what appeared on third-generation Corvettes in 1968. Another styling cue that made production was the design of the tail lights, which are nearly identical to that found on first-generation Pontiac Firebirds. Indeed, the high performance and sensuous styling of the Banshee may have led to its demise. Head of Pontiac John DeLorean called this car the "Mustang Fighter" and rumor has it he fully intended to bring it to production. However, his bosses at GM felt that it would be a threat to the Chevrolet Corvette in that it would steal sales from the Corvette and also that (if DeLorean had his way) it could out-perform the Corvette as well.
This did not sit well with GM execs who had marketed the Corvette as their top performer. The Banshee would have had equivalent horsepower, yet weighed 500 lb (227 kg) less than the Corvette and so would have been a potent package. It was able to reach 60 mph (97 km/h) in second gear. GM executives instructed DeLorean to cease further development in 1964. In a move loaded with irony, a memo to GM's head of design, Bill Mitchell, dated September 10, 1965, instructed Mitchell to have his staff update the XP-833 exterior clay and interior bucks “reflecting a Chevrolet design for the two-passenger version coupe." And so it was that the XP-833 project was revised to become the C3 Corvette against which it had been forbidden from competing.
Source: Wikipedia (original)