Which makes me wonder if the % profit is higher on premium gas, if they are marketing it over regular. Unless the vehicle is tuned to run it, premium gas will do absolutely nothing for you. You should really stick to the grade that … Our naturally aspirated motors are deigned and tuned to run on 87 octane (or higher). It is different only in octane rating. I dealt with different gas companies and octane levels, and so far I stand by Shell’s Premium gas. I get a better response, quieter engine, and better fuel mileage.
FWIW, premium gas has the same amount of energy as regular unleaded. In some cases you can do more harm than good by using premium gas because it can lead to carbon build up, and you may get worse mileage because you are not getting a clean burn. It is really mis-labeled because it is not better than regular gas. I get about 20 to 35 miles more on the higher octane. Our naturally aspirated motors are deigned and tuned to run on 87 octane (or higher). But you or DAX15 can remember and elaborate further, I would be very interested in what the gas engineers said.