Is high-octane gasoline worth the extra cost?

John Paul, AAA Northeast's Car Doctor, answers a question from a reader who is tempted to pay more at the pump for premium gas.

–AP Photo/Elise Amendola, File

Q. I have a 2010 Honda CR-V. It has the larger of the two engines offered. In the old days, I remember adding high octane gas every so often to clean or clear parts of the engine. Two months ago, I did just that, and the performance issue cleared up. Additionally, I noticed I got better mileage with the premium fuel. Then, last month, we took an overnight road trip to northern Maine. I put in two-thirds of a tank of the highest octane gas that was available at the Sunoco station. I know that highway driving will improve how many miles I get per gallon, but when I got back, I drove almost a week in city traffic, and I still did better than before. How bad is it to pay for the higher octane and better miles-per-gallon?

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A. As a general rule, using premium fuel in a vehicle that doesn’t require it is a waste of money. There are some cars that recommend using premium fuel to maximize the efficiency and performance of the engine. AAA did controlled tests on some of those models and found that the miles-per-gallon increase didn’t offset the additional costs for higher-octane fuel. What could have happened with your vehicle is that Sunoco and many other name-brand fuels are considered TopTier fuel. TopTier fuel has additional additives that clean fuel injectors and combustion chamber deposits. Your cleaner, smoother-running engine will also result in fuel economy closer to when the car was new.

John Paul is AAA Northeast’s Car Doctor. He has over 40 years of experience in the automotive business and is an ASE certified master technician. Email your car question to jpaul@aaanortheast.com.