May 13, 2006
Ever since they started becoming widespread I have been a fan of pay-at-the-pump gas stations. That I don't have to go stand in line behind someone buying a lifetime supply of losing lottery tickets, or brave the stale, smoke-tinged air of some service stations is fine with me.
Part of the pay-at-the-pump experience is waiting for your card to be approved before you pump your gas. I've often wondered about the algorithm behind that approval process. Is it programmed for a set amount, say $50, or does it input the current price of gas and multiply by an average amount of gas purchased, perhaps 20 gallons. Lately this curiosity has increased as the price of gas has increased. If the pumps are set to pre-approve a set dollar amount it is likely that rising prices have forced all the pumps to be reprogrammed to have a higher set point. Filling my 22 gallon tank with 91 octane regularly exceeds $50 now, and on occasion tops $60.
It would be easy to pre-approve $100 on the thinking that few vehicles would hold more than 30 or so gallons of $3.00 gas. But what about the poor guy who just wants to top off his tank before leaving town and who only need 5 or 10 gallons (a $30 purchase say) whose card has a currently limit less than the $100 set point? This person would be denied the sale not because they didn't have the funds, but because they didn't have the minimum funds to get approved.
I realize that the gas stations are more concerned about getting guarantees that the credit and debit card sales made at the pump are in fact viable in terms of ability to pay. And I suspect they are willing for a certain percentage of customers to be denied in the interests of not losing money on non pre-approved sales. As a developer of software I am always curious about the larger social implications of seemingly minor programming decisions.