Is a gallon really a gallon?

MECKLENBURG COUNTY, N.C. -- As the price of gas goes up, so does the number of complaints from people who suspect they’re being scammed at the pump.

Inspectors with North Carolina’s Consumer Services Department took WCNC along as they tested gas pumps.

“It is a commodity that you don’t actually put your hands on,” said inspector Gerald Brown. “There’s a lot of trust involved that the dispenser is giving you the accurate amount.”

Besides annual inspections, state workers are checking out pumps that customers called in as suspicious, thinking that they paid more than the actual gas they got.

"We run any type of testing that we can to make sure that equipment is going to be accurate,” Brown said.

Inspectors started at a Shell station at the corner of Albemarle Road just inside the Mint Hill city line. They pumped 5 gallons into measuring containers, one pump at a time.

Official measurements are compared with the gas station fuel receipts.

“But everything checked out,” inspector George Grier tells the store clerk.

Next, inspectors headed to the Sam’s Mart on Monroe Road, off Highway 51 in Matthews.

"Scamming is very hard to do," warned Brown.

For about 1,000 inspections, the state uncovers one problem and it's usually equipment failure.

"Maybe a small meter jump when you first start up and that's because of a leaky nozzle,” Brown said.

Pumps at the Sam’s Mart passed the test.

In Brown’s 28 years, he’s never had a case where the gas station tampers with equipment to rip-off customers.