Pontiac Aztek
General Motors got credit for trying new concepts in the 1990s and 2000s. But many of these concepts, such as the dustbuster vans, were downright hideous. One such hideous offering was the Aztek, a car so bad that it bombed within the first couple of years. The Aztek had undersized wheels and an ugly gray body cladding up the sides (via Hot Cars).
Pontiac phased out the body cladding for the 2005 model year, but it was too little, too late. The car already suffered from a bad reputation and lackluster quality. The Aztek was notorious for transmission failures as well as overheating problems. The first year of the Aztek was the most problematic, and many issues were worked out over the remaining model years.