I was once forced to put some premium in the rex at some citgo out in the country. I was on my way to an autocross with plans to arrive and autocross with between an eighth and quarter tank of sunoco 94, the only gas I use. Thanks to shoddy directions from a fellow autocrosser, I burnt up too much on the way, and reluctant to compete with the low fuel light on for fear of fuel cut around corners I had to go citgo, the only gas in the small town.
My car ran as if I had filled it with diesel. It was a week before my car ran correctly. Never again.