Slide-out tray systems for a vehicle comprise: a pair of tracks provided inside the trunk of the vehicle in a vehicle length direction; a tray mounted on the tracks; a bar pivotally connected to a connector part connecting the trunk lid to a vehicle body panel; and a cable connected to the tray and the bar and having a length such that when the trunk lid is open, the tray can be pulled out of the trunk in a rearward direction without interference by tension applied to the cable. With the systems, inconveniences associated with loading and unloading items can be eliminated or reduced.