Can the property management park the car in front of the owner's private garage and rent it to other owners?

You can look at your house purchase contract and garage purchase contract, which should have the relevant agreement on the ownership of garage and parking space. If not, the land in front of the garage door belongs to public land, and the property has no right to do so without the owner's authorization to entrust the property parking space and allow it to be rented. You can ask the property to stop the infringement and remove the obstruction.