There are plenty of 1-year-only cars as far as designs; more if one considers unique parts or features.
I'm enough of a gearhead that I can appreciate other manufacturers when they do something notably cool.
As a result, I've enjoyed a couple Mustangs, 911 Porsches, Z28s, El Caminos, Tri-fives, and a GMC Dually.
One of my dailies is a Nissan Pathfinder that's been utterly bulletproof and capable.
From assembly line workers to CEOs, folks in the industry have moved from one make to another, and often accomplish cool things at different places.
I've been addicted to Mopars since childhood; but it's a bigger world than that, and a wider scope has been fun and educational.