SEATTLE – Consumers have been debating for years whether the more expensive gasoline is really different from the cheaper gasoline. Half a century ago, the gasoline flowing from competing stores was not the same, but that’s no longer true.

“All the gas that goes through the pipelines is identical,” Jeff Lenard, NACS spokesman, told KIRO-FM. The difference comes at the end when companies mix in additive packages before retailers receive the fuel, such as Shell’s “nitrogen-enriched” blends and Chevron’s Techron.

“These additive packages are proprietary,” said Lenard. “Most of these different blends say they're somehow preferable based on customer studies, but all of the gas sold meets federal standards.”

The additive blends also factor into the price of gasoline. “Fuel brands that are sold significantly less than other places in the same area, it's probably due to a business strategy,” Lenard said. “If you're selling it for less than the competition, you are probably looking at making money somewhere else.”

The 2013 NACS Retail Fuels Report has all the details about how market conditions impact gasoline prices—and what to keep an eye on this year.