What are rare factory options you have seen on vehicles?

1960’s era Cadillac and Lincolns with power vent windows. Go figure.

@VDCdriver When Ford designed the Maverick, they cut corners everywhere, from having no glove box to non crank back windows on the 2 door models. Our 1971 Mercury Comet, a clone, had those pop out rear windows. The kids loved them and never tired of opening and closing them. I still remember that annoyoing “thunk” sound when on a trip.

fully adjustable, power, heated, bucket rear seats . . . in a car

Probably not that uncommon on ultra high end cars

I owned a 1971 Ford Maverick Grabber. I had some lights in the grille (not the parking lights–it had those as well) called “sport lights” There was a switch on the dashboard to turn on the “sport lights”. I have no idea what the purpose was. They gave hardly and light.
Speaking of non-options, my brother once owned a 1963 Buick LeSabre with a 3 speed column shift manual transmission, no power steering and no power brakes. He got the car at a very good price as a used car because it did take some effort to steer and brake.
My dad owned a 1947 Desoto with a lighted hood ornament.
Another feature I remember is that some cars in the1940s had lights under the car. My 1947 Pontiac had the socket for such a light, but the bulb and lens were missing. I never understood the purpose for this. Also, one option on the 1939 Chevrolet was a two-level horn switch. The horn was honked by the button in the center of the wheel, but there was a switch on the dashboard marked “country” and “city”. I think the softer tone was for city driving.

The old Renault Dauphine also allowed you to choose between a “city” horn and a “country” horn.
If only it had allowed you to drive more than 1,000 miles between mechanical breakdowns…

Removable hard top with a built in electric sunroof

One rare option was the “glass top” (actually Plexiglas) offered on 1954 and 1955 Ford and Mercury cars. The Mercury model with this feature was called the “Sun Valley”. I’ve forgotten what the Ford designation was for this model. It was not a popular option.
I also remember the air suspension that GM offered on Oldsmobile, Buick and Cadillac lines in 1958. It didn’t work very well and I think was abandoned in 1959.

I just thought of another one–in 1941, the Chevrolet offered a radio with a short-wave band. It was discontinued and never returned because of the war and the possibility that such a radio could be used by the enemy.

@Tridaq The Ford with the plastic roof was the original “Crown Victoria” Not many were sold; they must have become very scratchy as time went on.

A friend of mine had one of those air suspension 1958 Chevrolets. They were a pain as one corner of the car would be higher than the other. They were all recalled and refittied with regular coil springs. Later Lincolns were a bit better, but as they aged they had the same problems.

How about a tent option? It was a factory option as I recall

I had a colleague who owned a1959 Imperial with a stainless steel roof. Also, I have seen a Ford Tmepo (I think a 1987) with the optional V-6 engine.

“The Ford with the plastic roof was the original “Crown Victoria” Not many were sold; they must have become very scratchy as time went on.”

Actually, Ford’s counterpart to the Mercury Sun Valley was called the Skyliner.
It was essentially a Crown Victoria with a tinted glass section in front of the chrome strip that went across the roof.

Neither the Sun Valley nor the Skyliner sold very well, due to the high price and the “greenhouse effect” inside the cars in the summer. Even with tinting in that glass roof panel, the heat load from the sun was incredible in those cars.

The 1953 Dodge Coronet V-8 offered two automatic transmissions: 1) Gyro-Matic and 2) Gyro-Torque. The Gyro-Matic had a fluid coupling between the engine and transmission, but the Gyro-Torque had a torque converter. However, the torque converter on the Gyro-Torque as well as the transmission shared its oil with the engine. The Gyro-Torque was not very popular.
Both transmissions were not fully automatic as one had to release the accelerator to shift.

Gyros belong in a Greek restaurant

Kaiser has a model in the 50s that was called the Travelall. It had folding seats and the back hatch opened with a canvas insert that created a tent of some sorts. It slept 3 in a pinch.

And then there are options that show up on way more cars now than they ever did from the factory, like ‘Continental Kits’, wire wheels, and wheel well spats. How many '57 Chevys actually came with all those?

Wasn’t there a VW, back in the '90s, that came with a bike rack…with a Trek mtn bike on it?

These things were all aftermarket add-ons. The top line Bel Air had whitewalls and “Deluxe” wheel disks rather than plain hubcaps. A continental kit came with frame extenders and filler panel between the bumper and the body. Flaps, spats and fender skirts were also add-ons form specialty suppliers.

I guy I used to work with had a Ford Aerostar minivan that had a manual transmission. Only one I’ve ever seen. I had a 1980 New Yorker that I bought used that had a stainless steel roof and a “special handling package” option. I never saw another one with those options, though admittedly the car itself was somewhat rare in my neck of the woods, at least by the time I had it, which was from 1993-2000 (and that was the car I had that wouldn’t die too)

While not a car manufacturer option, some may remember or have heard of the swamp coolers that were used in place of A/C units and were popular in the Southwest part of the country.