In New Jersey, that responsibility belongs to The Office of Weights and Measures. Action News was there as Inspectors arrived at a Lukoil station on Kaigns Ave in Cherry Hill for a surprise inspection.
Over the last two weeks the state Division of Consumer Affairs' "Octane Task Force" has checked 213 gas stations statewide with on-the-spot testing of octane levels in the gas being sold.
"We're looking for octane tampering. We're looking for adulterated octane. We're looking for water in the tanks and we're checking to make sure a gallon is a gallon," said Robert Campanelli of the Office of Weights and Measurements.
The results showed this station checked out fine. The 93 octane coming out of the pump measured just as it should. Owner Gary Mathoan says he welcomes the testing.
"If you're paying for it you need to know exactly what are you getting for it. There's no doubt about it,"" Mathoan said.
Making sure the octane levels are accurate is important not only so you get what you pay for, but because - if they're off - it can cause problems for your car.
"If you are getting less octane in your engine than that which your car requires you'll have a knocking and a pinging," said enforcement supervisor John McGuire.
"If you're paying more money for better gas you want to make sure you're getting the good gas," said customer Katherine Sposato.
Of the 382 samples taken statewide recently, all but 22 have passed. Violators can face fines and even shutdowns.