The tip revealed by the email is that if the hose and nozzle are on the right side of the pump symbol, your fuel-filler door is on the right side of the car. Left side, left door. So you should never again pull an unfamiliar rental car up to a gas pump and only then discover that the gas cap is on the other side of the car. This is "the World's Best-Kept Auto Secret," the email claims. Why don't car dealers share such important information with buyers, it gripes? Why isn't it in the owner's manual, it whines? Why don't mechanics tell their customers, it rages? Why has this conspiracy persisted, it stamps its little foot?

Because it isn't true, that's why.

The International Organization for Standardization, usually referred to as the ISO, dictates the shape, color, size, and design of such icons, and the ISO some time ago decreed that the fuel-gauge symbol would be exactly as it is in the photo that leads off this rant, with the hose on the right side regardless of whether the car's fuel-filler door is on the right, left or (in the case of older Jaguars) both sides.

The fact that the symbology makes no sense as postulated by whomever originally wrote the viral didn't bother them. For in fact any sensible graphic designer would create an icon that represented an imaginary gasoline dispenser if it was meant to help the driver: The hose would be on the left of the icon if the car's fuel-filler door was on the right, so that you'd in effect "drive up" to the pump shown on your instrument panel.

But I'll bet there are still a few people out there who don't know that the little triangle next to the pump icon (you can see it in the photo I took of our Volvo's fuel gauge) is what, on some cars that have this brilliant feature, indicates the gas-cap side of the car.

Perhaps that is the world's biggest car secret.