19: 1974 to 1978 Ford Mustang II
We already know the Pinto was a disaster for the company when it ended up causing controversy. So the next generation Mustang at the time was based on the Ford Pinto platform. You might question a Ford Pinto-based Mustang model as most enthusiasts did at the time. The car never achieved the same sales success as the previous Mustang models (via Motor Biscuit).
The design of the Pinto-based Mustang was contrary to the formula that the company had already put forward with the previous generations of the car. The compact dimensions and underpowered engine weren’t compelling enough to entice the next generation of buyers. The Pinto-based Mustang ended up being a sales nightmare for Ford. This is by far one of the most underwhelming generations of the car and a black mark on the otherwise storied heritage.