I had heard that too. I did find something interesting when I was commuting by motorcycle and doing about 17,000 miles per year: For the summer/winter blends, I noticed about a 10% drop in fuel economy with the oxygenated fuel. That was during the time of MTBE, although some brands used ethanol instead. I have not researched the difference in blends used currently, so there may not be much difference between brands anymore. I'm no longer noticing the seasonal difference, so maybe?

 

True-I live in AZ and cringe at that state but for my contribution I have only used Costco Top Tier fuel in mine and have not had any issues to date. I have been fueling up there since I bought my F Type years ago.

 

I only use top tier gasoline.
Here is a website to search for stations considered to have that. By the way, Costco is on the list.
TOP TIER™ Station Finder - TOP TIER Station Finder