@Aleksa1 If there are available, free parking spots in front of your building, and the area is safe to leave a car, then it doesn't seem necessary to offer your garage. But if it's possible for a guest to find that all of those spots are full, then you couldn't advertise that there was free parking. And if cars on the street may get broken into, that's not a good scenario, either.
But unless offering your garage will inconvenience you in some way, like you'd have to park your car elsewhere, it doesn't seem like it would cost you anything to offer it for free, so that may indeed make it attractive to guests.