11: Mercury Cougar
The Cougar was always the also-ran brother of the Ford Mustang, and there wasn’t anything unique about this car. The first generation especially has risen in value due to the current muscle car bubble. But at the end of the day, the car isn’t worth the price tag and will only depreciate as time goes on (via Repair Pal).

The car was a confusing mix of muscle car and luxury, something that GM had tried with the Camaro Berlinetta and failed miserably. There are sports cars from this era that are worth considering, but with the current inflation, the Cougar just isn’t one of them. You just won’t justify the high price tag you spent on the car.