On an 86 fiero:
Popup headlights - Silly maybe, and out of fashion. I don't know of any new cars that use them, even the Corvette dropped them.
Manual steering - It's a feature to me, I'd pay extra for it on a newer car if I could. I dislike the disconnected feel of power steering. It makes me feel like I'm driving by remote control and it's just unnecessary IMO, especially on a small car. (power steering setups w/ power disabled are much heavier, that's not what a manual steering car feels like)
transmission dipstick
open steering wheel - airbags have precluded that
serviceable tapered roller wheel bearings, and easily replaceable shocks separate from the spring (true only in the front on my car)
Seatbelts that set their position and stay there. If they get tugged on they will loosen up slightly and stay in that position. Give them a second tug and they retighten. It's like operating a set of window blinds.
Modern seatbelts are constantly ratcheting tighter and tighter and never stop. My understanding is this behavior was mandated by the feds.
Simplicity in general - essentially banned. No way to meet all the modern political mandates with a simple car anymore. Today's cars are so absurdly complicated it's as if they were designed by a government committee - and they pretty much were.
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couple things that aren't on my current car:
Hand crank windows - I don't have them on my car, but wish I did. Power windows must be the most overrated feature ever invented. They are a nuisance and a negative value to me. Manual windows always work, they don't break, you don't need to turn the car on to use them, and you don't have to wait for a silly motor to do what you could easily do in half the time.
I could maybe go for power window on the passenger side but I would always want a hand crank on the driver side.
luggage rack - my previous car had one of these. I even used it once. Almost nobody ever used them but I have nothing against them, they look better than a decorative spoiler anyway.