For those of you who aren't aware check this out. There is also a video about it on yahoo.com today. Trick is, some stations don't even display the higher charge you'll pay per gallon for a credit card purchase: Cash vs. Credit Card: Gas Stations Charging Different Prices - Consumerism Commentary: A Personal Finance Blog I remember back (perhaps too far back for many of you) when this was done before (during the last major spike in gas prices). This was before the electronic pumps that can automatically switch the price on its own. The way it worked was that some stations (mostly EXXON in my area), had a cash price and a credit price. The cash price was displayed on the sign, the credit price set on the pump. If you paid in cash they'd add the difference (in extra gas). Some stations had conversion charts to show you how much more you got for cash purchases, but too many didn't... and they almost always shorted you by several cents worth, regardless. Pennies to you, but to them, undoubtedly thousands of extra gallons per day. (From those memories alone I still tend to avoid Exxon service stations unless left no other choice). Nowadays, according to the report, the pumps at the stations that charge two different prices change automatically, probably without your notice if both prices aren't posted. The wonders of modern science, eh?