Cars may be more advanced now than back in the day's, but still you are asking the the car to perform more things than it was designed to do, thus causing premature wear out on the components. The car was designed to burn a higher grade of fuel for a reason and thus the ecu was tuned to those parameters. Taking a chance on destroying your car to save $120 a year versus the cost to replce worn out componets does not make any sense to me. I know from working on SAABS, customers using the higher octane gas was much better and the cars had less drivability problems than those who used the cheap 87 gas. I have always used the better gas with whatever car I drove that required it. And even in my Durango 4.7 there is a big difference in performance, just from 89 to 91+ octane, and thats all I use in it now. But you do what you feel is best, but I am sure you will find a lot of us xfire owners use premium gas all the time.