Last year, they found roughly 4 percent of stations made dispensing errors. Half the errors benefited the station. The other half gave drivers more gas than they paid for.
One gas station owner says stations are not benefitting from record gas prices. And he says they're even seeing a decline in a key part of their business.
"Before when you filled up your gas tank for $40 you had like ten extra bucks to spend on pop, sandwich but now all your money goes to gas you can't afford to buy any other products at the convenience store so that diminishes our profits even more," said gas station owner Kanwalveer Singh.
In Chicago, inspectors say complaints about gas stations are up but they're finding fewer problems at the pumps they check.