19. Pontiac Aztek
When they presented it in 2000, the Pontiac Aztek was a good idea on paper, at least. The mid-size crossover model with its sharp new styling, decent engine lineup, and plenty of interior space was a modern concept at the time. Pontiac was eager to present it to the public since the overall sales of the brand were poor. They thought a new model would boost their popularity and bring new customers to the dealerships.
The plan was sound, except for one thing, and that was the design. Somehow, the Pontiac designers managed to push to production one of the ugliest cars they ever made. Even from a distance and 17 years after the first Aztek saw the light of day, it is still a car with a design that makes no sense whatsoever. Every design component, and the car as a whole, is extremely ugly. Also, the interior is questionable. The same person who designed the Aztek went on to design the great-looking Corvette C7, so it is strange how he managed to do such a bad job at Pontiac. The pure ugliness of the car, as well as the bad fit and finish quality, is what sealed the fate of the Aztek despite having some good features.