SFist Photo: Is this a fair pricing scheme?

Just sort of wondering here. We recently witnessed a woman complaining about her gasoline purchase at a San Francisco service station. She only wanted gas (without a car wash) and assumed that the price on the left side of this sign is what she would pay per gallon.

After pumping she figured things out, calculating she lost about five bucks due to the car wash discount scheme. Then, after raising a fuss she was offered ... a further discount on a car wash. Didn't make her happy.

Certainly this particular driver was misled. On purpose? Would Big Oil do that? Are other drivers getting misled as well? (Don't get us started on the whole premium vs. regular thing. Or the Peak Oil thing.) We're sort of curious - is this a normal way to advertise gasoline? O.K. love you bye bye.