Why would a garage not need a mezuzah? Don’t storage rooms need a mezuza?
Storage rooms are obligated in a mezuza, as is brought in Shulchan Aruch Y:D 266:1,2. However there are various opinions with regards to what characteristics are required of this storage room. Some Rishonim hold this is only a storage room which has a direct opening to a house [Shu”t Natronai Gaon Y:D 267]. The Avnei Nezer [O:C 302] writes it must be a place fit for a person to dwell. The Rambam’s opinion is that the room must actually be used for a person’s personal needs as a room in the house, at least from time to time. Because of all these doubts most contemporary poskim rule not to make a bracha on typical storage rooms when affixing a mezuza [Shevet Halevi 2:156, Minchas Yitzchak 4:89, see however Shu”t R’ Akiva Eiger 66].