46: Pontiac G6
The G6 was probably one of the most heavily marketed cars to ever fail. This was the car that Oprah famously gave away to every member of her audience. The G6 was supposed to be a revolution, but in reality, it fell short in just about every aspect of the design (via Car & Driver).
Its reliability was questionable at best and its performance was lackluster. Underneath the car shared a platform with the rest of the GM lineup that was available. There was nothing that was truly unique to this car and consumers were able to tell the difference right away.