Don't know. Of course the gauge will be way off. You have to check it by hand,then add 6% more miles cause your odometer will be off too. Haven't done that yet. However, I usually lost about 2mpg with my diesels in the past.
ecoscrew. Please let me know if the calibration "took" Just check it before and after with a hand held gps.
Last edited by AC Man; 02-07-2012 at 05:45 PM.