Thanks guys. A few specific comments:
Jarrid: as always, thanks. I actually bought a black light bulb in the spring when I was first dealing with this issue, but it was so dim that I couldn't see anything. I don't remember if I tried it in the dark, which I will do tonight. As for an exhaust analyzer (I know I told Ken I would ask about this tonight, but I am taking a break right now), there is a place across the street that I can call and ask. I'll do that tomorrow if necessary.
Tom: I am hoping you have hit the nail on the head. While my drive to work is only 10 minutes, I just checked the coolant level and it wasn't bad. It was a little lower than when I left the house this morning, but I had accidentally over-filled it, so I expected some loss. I have a couple of errands to run on the way home, so I will be doing some highway and some stop and go driving. That will be a better test and (Todd) I made a careful note of the coolant level when I just checked it.
Tracy: I have checked it while revving the engine before and still cannot find any evidence of leaks. That is one of the many baffling parts of this mystery. And, while I haven't parked on a dirt road, we are doing some construction at my house and the driveway is covered with dirt right now. I have yet to notice anything unusual under the car.
And finally, Todd: Yes, I am a longtime owner, but NOTHING is beneath me, especially at this point. Almost everything I know about Alpines comes from reading this forum and asking LOTS of questions, so please never worry about insulting my automotive intelligence. Oh, and as for the heater core, I had the heater on for most of my drive to work this morning and there was no evidence of any fluid in the jug I had set up. I did shut off the heater before I arrived, so I will try leaving it on this afternoon, just in case that makes a difference.
As always, thanks everyone! I will be bringing the car to the Invasion, even if I have to tow it!