How do I track down the owner of an old car in my office parking lot?

Sounds like a Continental Mark III or Mark IV, and the hidden headlights plus that big roll on the roof put it somewhere in the 68 to 78 range. The wire wheels are interesting since most of those left the factory with turbine covers, so either an earlier owner swapped them or somebody ordered it that way. Either way, trim all intact and paint still glossy under the dust means it's been cared for, not just parked. Those cars rust from the bottom up when they sit outside, so what you're seeing is a good sign.

The wiper note is exactly what I did in a similar situation. There was a Buick sitting at my old shop lot for months and I tucked a short handwritten note under the wiper that said I was a car nut, I admired the car every day, and if they ever thought about selling to give me a call. Kept it friendly, no pressure, no mention of money. Got a call two weeks later from a guy whose wife had passed and he couldn't bring himself to drive it anymore. Didn't end up selling to me but we talked for an hour and he showed me the engine bay. Worth the stamp for the story alone.

A few tips on the note itself. Write it by hand and keep it looking normal,Typed printouts read like a scam. Skip anything that sounds like I'll pay cash today because that reads as a lowball flipper and those get tossed. Sign a first name and give a phone number, not just an email. And slip it under the wiper on the driver's side where it won't blow off.

If the note does nothing after a couple weeks, check the registration sticker or inspection sticker for the month it expires. Lots of these once-a-month cars show up right around renewal time, usually on a weekend or the first of the month. Come in early and hang around the lot then. Person who owns a car like that is probably an older guy who'd love to talk about it, so the conversation will start itself once he pops up.

One thing that helped me pin down a Mark III vs a Mark IV in a friend's driveway years ago was the quarter glass, since the III has that oval opera window and the IV went to a wider shape around 72, so a quick look at the rear pillar might narrow the year before you even talk to anyone. Also the door edge sticker usally lists the paint code and build date, and cream over a padded vinyl roof is a fairly classic combo for those. If you do catch the owner, the dust is your friend, it means the paint has been sitting untouched, so ask about the car first and let the sale talk come up on its own.

Funny, my buddy had the same setup at his office building years ago. A old Thunderbird just sat there for months and the note under the wiper got him nowhere. What actually worked was catching the guy on a Saturday morning when he came to drive it. They ended up chatting for like 45 minutes and it turned out the owner just kept it there cause his garage was full. Didn't buy it but still stay in touch. So yeah, do the note but also keep an eye out on weekends. If it's a once-in-a-while driver you'll catch them eventually.

Back in the day the lot janitor or security guard knew every car and every owner, that was always my first stop. Guards see everybody coming and going, and most of them are happy to chat if you slip them a few bucks for coffee. Failing that, I used to leave a note with a self addressed envelope tucked in the door window instead of under the wiper, rain never touched it and it didn't scream scam like a printed sheet. Also worth checking the tire wear and dust pattern on the glass. Even dust tells a story, a car driven weekly never builds it up the same way.

I'm on the flip side of this one. My dad has an old Fury that sat in our driveway for almost a year and some kid left a note on it saying he admired it every day on his walk to school. Dad talked about that note for weeks, way more than he ever talked about the car itself. So OP, don't stress about being weird, the worst case is they ignore it and nothing happens. One thing I'd add is mention you work in the building, that seemed to be what put my dad at ease, it wasn't some random stranger. Also kind of new here myself, what's the etiquette if the owner actually does want to sell, do you get an inspection done before talking price or after?

Update: the wiper note did nothing, so I took the Saturday morning advice and came in early. Sure enugh the owner showed up around 8 to drive it and we talked for a while. Checked the quarter glass like someone suggested, oval opera window, so it's a Mark III. He's keeping it, but said I can come see the interior sometime.