Since we're not likely to see the kind of trauma seen on the battlefield (especially when there's a fully stocked ambulance on the way if we do) I keep only a few things in a bag in the car. Stuff anyone can use. Some gauze pads, roller bandages, shears, tourniquet, and gloves. I also, always, have a bag in my back pocket with two pairs of gloves in it. That's about it.