Does running with premium fuel really give you better fuel economy?

It really depends on the vehicle. For instance, if you are driving an older vehicle which gets poor fuel mileage, it will not make a noticeable difference. On many newer cars though, you will find that it does make a difference. To find out on your vehicle, fill it up completely with regular, and record the mileage on the odometer. Drive it until the tank is near empty, then fill up completely again, this time with high octane. Record the mileage on the odometer again, and subtract your original mileage recording. The difference is the number of miles you drove on that tank. Take that number and divide it by the number of gallons that you put in your tank the last time, and you will have your fuel mileage on regular gas. Since you will now have premium gas in your vehicle, repeat the process to find the mpg with premium. This way you will find out how many miles per gallon your personal vehicle gets on both. Now if you want to find out if the difference in fuel economy is equal or better than the difference in price, in other words, which fuel is cheaper per mile for you to burn, simply divide the price of each grade of gas, by the miles per gallon that it produces in your car. Example: I know my vehicle gets 20mpg on regular, and 28mpg on premium, regular costs 2.39 per gallon, so 2.39/20mpg= 12 cents per mile premium costs 2.59 per gallon, so 2.59/28= 9.25 cents per mile. Therefore it is cheaper to buy premium. You must do the figures yourself, because no 2 cars are the same. Concerning ethanol, you can only burn ethanol mixes if your vehicle was specifically designed to burn ethanol. Ethanol is more of an environmental advantage than an economical one.