This is where phone cameras come in very handy. When you get your car, do a full loop around it, snapping shots of each side. Make sure the shots are time and date stamped. Note any dings or dents on the paperwork from the agency, but keep the photos on hand too. When you return the car, take another set of photos. If any charges mysteriously end up on your bill, you’ll have evidence of what did and didn’t happen on your watch.