Good points -- I agree that your suggestions would be optimal for nap-friendly companies.
At this particular workplace, it took 90 seconds or so for me to walk from my desk to my car, so it wasn't a big deal. I was also used to the routine, and preferred the certainty that no one would ever walk in on me.
Sometimes. Managing that issue was definitely something I thought about, and it affected where I parked and what direction I would point my parked car to avoid the sun. Usually I just rolled the windows down a few inches, though, instead of running the AC. I live in a temperate area and I have more tolerance for temperature swings than some. And I was usually setting my alarm for 20 minutes, so I wouldn't be there that long.
I feel guilt for this where I work. It gets to 120f outside here during the summer. It's not great to run the car for just ac, but I benefit from the alone time.