Myth #1: Premium gas pays for itself.
The logic is to use only the highest-grade gas, and your car will need fewer tune-ups and get better mileage. Those extra cents per gallon are a good investment. The car runs more efficiently while burning fuel better.
With modern technology, the best fuel economy results from the best ignition point. Additionally, the car will eliminate road and knocking noises. Personally, I run only high test in all of my vehicles.
However, some experts disagree. The difference between 87 and 93 octane is relatively insignificant. You will realize neither better mileage nor fewer maintenance bills by purchasing supreme. Unless the car is supercharged or the model specifies that it needs higher octane, choose the inexpensive fuel. Buy the cheapest — unless you are in Mexico, where the cheapest is closer to kerosene.