It may not be ethical, but for several months last year I was able to make an automated gas pump unit pump more gas than I paid for … significantly more. It all started one fine sunny day when I decided to purchase a pre paid 10.00 gasoline card. The gas station was designed so that no attendant was on duty and everthing was supposedly automated. Being the inquisitive person that I am I only filled my tank to 9.50 cents. I then turned off the pump. Reinserted my ” lovely ” pre paid 10:00 card and proceeded to do it a second time. Ahha what a thrill ! … I could pump FREE gas … camera’s be damnded ! I found out that I could usually get a 10:00 card to provide me with about 29.80 worth of gas if I figured correctly & took along an empty 5 gallon container for overage. Over the course of time I even went so far as to show the manager how their system was faulty. Her reply was ( shoulders shrugged ) ” Big deal “. I’m happy to report that this process lasted until shortly before I graduated college. I’de like to thank Exxon for their sheer stupidity of the system they designed and let them know that I’ve used my savings to supplement my technology degree and continue my education. On a karmic note, the Cadillac I was driving blew up shortly after school ended ( as did the free gas , ’cause they fixed the problem ) … so yep, life has its ups & downs and everthing you do comes back to you … ( it was still fun stealing the gas … lol )