Hedging for the rest of us

My girlfriend has an amazing ability of driving and taken mental notes on gas prices. A 2 cent drop makes her very excited. I thought it was only her till I started noticing other people are obsessed too. People fill gas when the price drops (even if it’s a 5 cent drop) and don’t fill when it’s beyond some psychological threshold. The solution could be a hedging system, gas stations already have speed passes and this idea could be added fairly easily. This is how it works, you go to the pump (gas is at $2.39) and insert your card, and then add money to the card, e.g. 50 bucks (the station can put a limit). This amount is debited from your bank and placed with the gas station, you then start filling your car and can later use the same card to fill gas at the original $2.39 even though gas prices are now at $2.62. The Gas station might charge a small premium for the service but it will draw many more people to the station and its natural these people will buy coffee or candy or cigarettes... and that’s where gas stations really make margins..