Okay, help me figure this out. These pictures were taken within about a minute of each other. South of Market:
North of Market, catty-corner from the first one:
P.S. A sharp-eyed reader from the East Coast pointed out what I should have spotted: the sign at the bottom of the first picture, which explains $3.75 as the cash price. The credit-card price is $4.33, almost as much as the station across the street. If I had to drive in San Francisco, I'd be sure to have cash when I needed to fuel up.