EVERYONE CHANGE YOUR PLUGS! if you haven't in atleast 15k miles, do it! WOW the difference. my mileage has been slowly getting worse, and i didn't evne think aobu tit, but I've never change my plugs at 35k. Haven't evneput a full tank through yet, but looks like I'll be getting atleast 50more per tank. Not bad for $8. PLUS my car runs smooth again. not that I ever noticed much that it didn't, but I notice how much smoother it once was now. those getting knocking and thus using higher octane, this goes especially for you.