Who needs premium?
In NASCAR races we use 98 octane gas, unleaded (except at Daytona). You won't find it at a corner gas station. But you don’t need it. Using gas with a higher octane number than the one in your car’s manual generally means you're throwing money away. My own truck runs great on regular — that’s usually 87 octane — so I figure, why pay more?

Premium runs about 91. You might see lower numbers in high-altitude places, because atmospheric pressure affects the way gasoline burns. The octane number isn't about quality — it’s about how well gas in a cylinder resists burning before it should. Early burning can cause pinging or knocking and damage an engine. A car designed for premium may knock or ping on regular, but generally one built to run on regular won't run better on premium. - JIM FENNIG

Jim Fennig is crew chief for the AAA No. 6 Ford Fusion NASCAR racer. Use the Fuel Price Finder at AAA.com for gas prices in your area.