My candidate for the ugliest car ever made is the 1959 Cadillac. With the Pontiac Aztek, there is some function to its form. There is no function to the shape of the 1959 Cadillac. The high rising fins served no purpose whatsoever. These cars hit the road when I was a senior in high school. I thought they looked awful then and to me the design hasn’t improved with age.
In fact, the whole GM line I thought looked awful, but the Cadillac took the cake. My dad was driving a 1954 Buick in 1959 that had gone 100,000 miles (quite a few for those times) and had had no engine work. He thought about trading for a 1959 Buick. After a test ride with the whole family, we decided we preferred our old Buick. The seats on the 1959 were hard in the middle, making it essentially a 4 passenger car. The trunk was very shallow. The seating position was too low for all of us. My dad told the salesman “I’m not paying $3200 for a 4 passenger car”. Form certainly didn’t follow function for these cars. Some years later, my dad bought a 1963 Buick LeSabre. It truly was a comfortable car and had a great trunk. Somehow GM saw the light between 1959 and 1963.