Gas Pumps Dispense Less Than They Say | WHAT REALLY HAPPENED

Gas Pumps Dispense Less Than They Say

As if rising oil prices weren't bad enough, it seems that you might not even be getting all the gas indicted by the highly accurate looking meter on the pump. Blog An Entirely Other Day took a look at whether or not a gas pump can really measure to 1/1000th gallon accuracy, and the answer was "No".

The workings out say tell the story:

This means that the accepted inaccuracy of a gas pump is half a cubic inch (over half a US tablespoon) plus half a cubic inch for each gallon and never less than one cubic inch.

In short, the pumps are allowed by law to pretend four times more accuracy than they can measure, and if the pump is between tests, the tolerence is even greater. Sounds bad? Try living in the South (or in a New York Summer): the rules assume a temperature of 60ºF. Anything over that and the petrol expands, meaning you get even less in your tank for the price. Of course, this could always go the other way and over-dispense. But how would you ever know?