I recently purchased a new car - it came with a full tank. It has been a month now and I have unfortunately not kept track of where I was filling up it was simply who had the cheapest prices, although up until the last fill up it has been with Regular Octane. I travel same time same distance each week, relatively same volume of traffic, and have found that I do not get the same mileage with each fill up. My point? Who is checking to see if the Octane levels are what they say they are? Talk about YMMV!!!!!!