The terms and conditions indicate that we need to rent from "participating Budget airport locations". There's a regional airport near me (no commercial service) with a Budget car-rental center right off the property. In fact, when I use the airport code in the car-rental search on the DL website, this location pops up (despite the fact that it is not serviced by Delta and the location is off property). I wonder if this would be considered a participating airport location. I have a feeling this is going to be difficult to determine.