necks who made it big. this is "nightline," march 20, 2012. good evening, i'm terry moran. today more bad news at the pump. one expert told abc news he expected gas will top $4 a gallon in most states by next month. with high prices draining americans' wallets, some drivers are fighting back. introducing gas buddies, a smart phone app that's part of a grassroots effort to help you save cash filling up your tank. we rode along with some eagle-eyed pump watchers to find out how it all works. >> for kathy nestor, it's become an obsession. >> oh, my god, $4.25 on the corner. >> reporte...