15: Infiniti Q50
Car brands come and go, but Infiniti was positioned to be a mainstay player for a long time. What happened with the company was a fall from grace essentially due to lack of innovation. Infiniti cars were just not that much different from your run-of-the-mill Nissan models. Consumers turned their back on the brand and after a while, sales went into a slump.
Most of the Infiniti lineup is nothing more than a fully-loaded Nissan model, whereas Lexus has been innovating since day one. The Q50 failed to deliver on the core principles that consumers look for in a luxury brand, and that caused it to fail.