This cheat is about getting all garages for free.

* Open saved files. Go 2 your last saved game folder. 
  (Mostly it would be tha last.)
* Open "game.sii" with notepad. Search for such file:

  vehicle_garage : garage.albuquerque {
  purchase_price: 0
  city_name: albuquerque
  stored_vehicles: 0
  open: -->(false)

* Now in your file change "false" to "true". 
* Do not change any thing else. 
* Do this for all garage files.
* Thats it u done. 
* own all garages.