I sneak off to the parking garage at lunch time to have a Power Nap in the back of my car. Tinted windows mean I'm totally invisible, and I can get 25 min of good rest. It is a highlight of my day
In fact, I have considered one in case I just want to (for example) drive to a trailhead the night before for an early morning start, and catch some sleep in the car without setting up a tent and all.