7. Cadillac Cien Concept
When Cadillac first presented the Cien in 2002, the automotive world was stunned. The concept of a super sports car with a mid-engine layout, aggressive design, and brutal stance was something nobody thought Cadillac could do.
However, Cadillac proved them wrong with this fantastic car. They built it to mark the 100th anniversary of the company in 2002. The Cien featured a 7.5-liter V12 Northstar motor producing 750 HP and was allegedly a fully functional prototype. Unfortunately, GM never saw the potential of a Cadillac that could beat a Ferrari, so this beautiful car remained a dream.