Host: Which octane gas is best for my car? David Rizzo: Well, by all means the best gas is what the manufacture recommends. Look in your owner's manual in the glove box. That car manufacture designed it for a certain octane rating, stick with it. It is a false economy to drop down on octane. Yes, it's tempting. I can save ten cents a gallon if I go cheaper. Now, again false economy. The reason is because all of the sudden the car has to burn more gas to give you the same amount of performance. Modern cars over the last ten years, they are governed by computers and engine control module and it takes into account the octane. If it's too low, it says hey we need more gas. It's like calling down for more steam. By the same token you don't want to go up on octane. There is no gain by going higher. If your car calls for 87, don't use 89 or 91. It won't run any better. You won't save any more gas.