Your "increase" in gas mileage may be from a "placebo effect" where you pay more attention to your driving techniques while measuring miles per gallon. Of course, once you go back to your "normal" driving habits, the gas mileage will go down too. You can't really get the honest full picture by measuring the MPG from just one tank of gasoline. Keep a record of your fuel consumption for a month or so and THEN calculate your overall MPG and see what happens.
Some cars DO seem to like one particular grade of fuel over another. If you DO see an improvement in mileage over a long time, then go for the mid-grade fuel.
Your Corolla is designed to run on 87 octane fuel. Using 89 or 91 will provide not more power and no better fuel mileage. You may think you are getting better mileage and you may be because your are driving for better mileage. It is scientifically impossible for the higher octane fuel to give your engine more power and better mileage. Octane rating relates to how much energy it takes to ignite that fuel. The higher the octane number, the more energy it takes to ignite the gas. Unless your car is explicitly designed to run on high octane gas, using a high octane gas will NOT give your car better mileage. That's because the rating refers to how much energy it takes to ignite the gas, not directly to how much energy the gas puts out. In fact using a higher octane fuel may cause hard starts, especially in cold temperatures. The only thing you will get from buying a higher octane fuel than your engine needs is a lighter wallet.
If you believe you're getting better gas mileage with 89, there you must have one of those magic Corollas. Because there's no more energy in 89 than in 87. 89 only has more flame spread retarder.
It usually isn't noticible especially in low compression engines where 87 is the standard recommended by the manufacturer If your test covered several tank fulls of each blend it my be valid but you do not always get the exact same amount of fuel in the tank before the auto shut off clicks.
the higher the octane, the better the fuel economy. that number is the fuels resistance to burning.
Hi in studies back in the 1930's it was found the more back pressure a car had the better a car would do more miles per gallon and quieter to. so i really don't see your logic honestly.
Because the knock sensor isn't retarding the ignition advance.
ty youve proven my point, octane is not a measurement of energy content, bt flashpoint
I have been trying different octanes in my car for months and iv tried 87, 89, and 93 and 93 seems to get the same gas miles as 87 but 89 when i have cruise control on going about 75 miles im getting around 36 to 39 but with 87 i get 32 to 35. I ask this because I always hear people say it doesnt do anything unless you have a sports car that can handle the octane but I also hear people say it does get better mpg. I did the same thing with my old car nissan sentra and the digital mpg number went up on the car. The only thing Iv done to this car was change the muffler to a performance muffler to let the exhaust flow better which did help my car greatly.
