I had the mpg go to zero, but mileage still shows 3000+ and mpg is slowly increasing as I drive I stealth only... It is up to 6 mpg. (real mpg is about 125). I sent a pictur to my dealer with a few other glitches with 6.28 ( which i did not have on 6.15). I think the miss installed a file... But too soon to tell.