Ubiquity. Some cars are just everywhere. The PT Cruiser, the Ford Taurus, the Buick LeSabre, and all a manner of trucks are swarming around towns like roaches. It's nearly impossible to pull up at a light without one of these being present at the intersection.
However, some cars that enjoyed having a presence like this are impossible to find nowadays. My example is the 90s Buick Roadmaster Estate wagon.
I used to see these all over the place, back in the early 2000s when my grandma had hers. Now? I'll *occasionally* see one in real life and good luck to anybody who wants to grab one off of Craigslist. Before Cash 4 Clunkers took its toll a mint-condition example of bench-seated corvette-engined goodness could be had for $10 and some pocket lint. Nowadays, if one can even be found, it's rarely even a runner and hideously overpriced.
So what cars can you guys think of that are scarcities now, but used to be as common as crusty socks in a 13-year-old's room?