I always think of this when I have my laptop with me in the car. I worry that if I leave it in the car, a would be thief will walk by and see it. But, if I take my backpack out and put it in the drunk it is a huge signal that "my backpack has something very valuable in it!" to anyone who might be watching. Since you can get into the trunk by breaking a window and pushing a button, I think on net, it is safer to leave my backpack in the car.