Chevrolet Corvair
The Corvair was set to be the future of sports cars, but its design was so radical that it was dangerous to drive. The main problem was the design of the wheelbase which was much shorter than anything else on the market. Due to a lack of design testing, the Corvair was difficult to drive, especially in inclement weather (via Hemmings).
The Corvair cost General Motors almost a billion dollars in lost revenue and sales. The design of the car was updated later on but by that point, it was far too late. The damage was already done by the tarnished reputation of the car. Chevrolet took a huge hit because of this car and it took them years to recoup from it, but they did.