From the notion (1) that one is flying free as the wind as if on angels' wings, and (2) that one's guardian angel had better be on duty because the practice is unsafe. Compare also Jesus clip, Jesus nut, and Jesus bar. Regarding the various synonyms referring to various places or groups of people, see Mexican overdrive § Etymology.

angel gear (uncountable)

1. (slang, automotive, trucking, heavy industry) The neutral gear when used while a vehicle is moving, especially when it is used to freewheel so as to save fuel or to coast downhill faster than a vehicle can go in gear.

   Synonyms: freewheel; overdrive (euphemism); (variants, some bigoted and derogatory, some possibly so) Georgia overdrive, Jewish overdrive, Mexican overdrive, Polish overdrive

   Antonyms: creeper gear, granny gear, low gear

   Coordinate terms: top gear, overdrive

   Near-synonym: neutral