Wow! I didn't realize just how much power some cars use with fan blowers (especially on "high" setting). I wonder how common those fan motor numbers are with other cars? And if many fan motors have numbers that bad (which IMHO would just be pathetic, given how common energy efficient DC motors are these days), I wonder how hard it would be to swap in a much more energy efficient DC motor for the fan?

Hmmm... If power usage is noticeably higher when the alternator is on, that would be the one argument I could see for having a circuit/switch to cycle between alternator on and off.

Because if (and only if) the charging power losses are less than the losses due to the higher alternator voltage, you would actually be gaining a little (overall) by completely "cutting out the alternator" until your battery is partially discharged, and only then turning on the alternator just long enough to charge up the battery (then repeating the cycle). Heck, you could probably tie this to a battery charge detection circuit, so it happens automatically. And naturally, this would probably work better with a quality "deep cycle" battery, than with a normal car battery...

Of course, the mod that someone else mentioned, where they didn't even use an alternator, is the extreme example of this idea (since 0% alternator load, which is what a disconnected alternator gives you, is the theoretical "upper bound" of what lowering the car's electrical usage, but leaving the alternator connected, could buy us in increased FE).

And, we could also possibly gain something (even if the alternator remains connected), by hooking up solar cells (carefully placed in the car, so that sunlight can reach them through the windows) to the electrical system (to both "charge" things slowly when the car is off, and also to slightly lower the load on the alternator). Of course, finding a useful place to mount the solar cells might be a problem, and the cells do add a little weight (which can work against you)...

In my CRX, it looks like the "running lights" is what you get if/when I click the first switch position on my headlight switch (instead of the normal situation of switching to the 2nd position, to fully engage the headlights/taillights/etc). Even if your car isn't wired up this way, I bet it would be pretty simple to tap into that light switch position, and wire it up as just whatever you want for daytime "running lights". That would give you an easy/clean way to turn on your "running lights" without even putting an extra switch into the car. :D

Some car bulb power numbers.
 

A while ago, I was looking for power usage of various car bulbs (so as to get an idea as to how much power could be saved from going to LEDs). It was actually harder than I would have thought to get this info on stock car bulbs. So FWIW here are some of the links I found in my search:

1) Apparently, many pinball machines use standard car bulbs. With that in mind, this pinball resource actually has a lot of useful power info on it:
https://www.flippers.com/lights.html

2) Here's a table listing a few of the more common "running lights" in a car (or in the case of the website it is on, a van):
https://cybrvanr.tripod.com/bulbspec.htm

3) Here's a PDF file, made by a magazine/company dealing with renewable energy for homes. As it turns out, some solar/wind home power systems use car bulbs for lighting. With that in mind, this PDF has some useful info:
https://www.homepower.com/files/hp1-31.pdf

NOTE: While the largest gain per bulb are gotten by swapping out the highest power/light bulbs (such as the break/tail lights), the highest percentage gain is gotten by swapping out the smallest bulbs for LEDs. This is because the efficiency (lumens per watt) really tanks in very small incandescent bulbs, whereas LEDs don't have that problem. So swapping several small incandescent for LEDs, can easily gain you more power than just swapping a few larger bulbs..