We have allocated couple of parking spots at company's building, their count is about 40% of employee count. We organized ourselves into groups of 2-3 employees sharing each parking place and we co-ordinate our daily parking withing these small groups. (Occasionally also between these groups.) This works fine.

I have reasons why I am using a car only when really needed (5 times a year, 2% of overall business days) so the other colleagues sharing the spot with me have a benefit of great availability.

Some day (of those 2%), if I really need to come and park, would it be ethical to expect treating my request for parking with higher priority than requests of other colleagues (who use the spot 98% of time) who want to park there that day?