I can't understand what's happening, but...
If I happened upon a way to get gas for $1 - even just one gallon, I surely would NOT throw it away!
Maybe I'm not being super clear, but this is what i'm thinking:
1. Go to gas pump and pay with a vanilla visa gift card with $1 left on it
2. The gas pump immediately charges me $1 as a holding fee
3. I fill up my tank with gas
4. Throw away the gift card
5. The gas station charges the remaining amount (~$25) to my gift card later but is unable to do so, since it doesn't have any fees. Since it's a gift card, they have no way of tracking it to me right?