what I found with the MPG reported was that sometimes they are short and other times they are over,,,, so really adjusting it would not seem to work .
For example/ on the MPG screen the numbers do not move up by .1 s. (Now the instant mpg screen moves by .1 s. Which mean the average displays every so often (not sure how often it is programmed to give a new reading). So, when you pull in for gas and shut down the car it might have been 10 seconds from putting out the new average for the last time period.... I don t know but I don t think these are too accurate sometimes. Not sure I made my point clear?