I lost my corporate T&E card last month. OK, I left it at a bar. I didn't call the issuer for several days because I was worried about car reservations, including the car I was driving at the time. When I did finally call, I asked the agent to read me the last 5 charges. I wasn't shocked to find that I'd already been charged for the rental cars when I picked them up, and I never show my card to Avis. I think the airline's more interested in your ID than anything else. I've never had to show a credit card, although I do use one to identify myself to a kiosk.