My PSK includes 6" of plastic straw, folded into 3 parts and flattened. That takes very little room, or weight and provides a former for cordage or tape (which helps keep it folded and compressed). Another approach is to stuff the straw with matches or tinder or whatever, so the inner space is used. Six inches isn't enough to syphon fuel out of a car, but I hope it could help get at some inaccessible water.