I had mine calibrated on 8/8. I didn't notice any difference, but thought I would give it a week. I dropped from 38.9 to 38.6 mpg. I was hoping for an improvement. I took it out on the freeway and noticed that nothing had changed. As soon as I hit 62, here comes the gas. I noticed that the explanation on the screen shows reason for gas to be on was "high speed". I thought it wasn't supposed to be considered high speed until 85 mph...not 62. Back it goes.