This little topic of conversation regularly rears its head. I think the general feeling is that optimax works far better than regular or super, with more MPG and better performance. I have run mine on nothing but optimax (except for 2 tankfuls) for the past 8000 miles, and get over 40 MPG if steady, and 35-37 when driving hard. Its far quicker from the blocks too. It does involve planning fuel stops upto a week in advance sometimes, but its worth every penny.