I had a customer that had to make three trips to Texas from here in So. Ca. in his Lexus ES330, '04 I believe. He said he was going to try one trip with premium and one with regular because we had chatted about the claims of performance. I had been told for many years that premium gives better mpg. Well his "test" showed that the trip with premium gave him 2mpg and I did some calculating and that made premium use about 2 cents a miles cheaper than regular and better throttle responce and acceleration. And thats just my 'two cents"