This may sound crazy, but its true 90% of the time. My X5,3.0 has 240K miles, most everything is original. I am noticing that when I have a full tank of premium only gas I get amazing quick peddle/acceleration response. Even the slightest touch and the X takes off smoothly. No issues. However, as I get closer to half tank it starts to become sluggish. At 1/4 tank or less its a very noticeable sluggish acceleration. It's so strange. Is this an indication that the fuel pump system is going? I don't have any SES light on either. Although, the other day, the tranny gear light came on, but it went off after starting it back up. What's going on with this amazing X5?
