Last night while I was in my my driveway at home I was at 53.3 MPG I turned off the car for the evening and when I started the car this morning I was 52.9 MPG. I lost .4 MPG just sitting.

Has this happened to anyone else?

 

It's explainable.....the FCD refreshes itself every 6 seconds, or about 10 times a minute.

So when you stopped, it was in "mid-refresh" in that six seconds before it was going to re-paint 52.9, but you turned the car off.

So when you turned it off, it resumed the incomplete refresh that was interrupted and updated you to 52.9

Same thing has happened to me at stoplights - I will stop and the car will go to AutoStop, then a few seconds later the FCD will change, and that was just because it was in the middle of an update cycle when I stopped.

 

You'll also notice that while the FCD updates every six seconds, you get a lot more variation (i.e. activity) earlier in the tank than later. Just after I reset the computer (after a fillup), I can sit at a stoplight and watch my MPG drop just from the idling. Regardless of where I'm at in a tank, I always seem to loose .4 MPG just starting the car in the morning.

 

That seems to make sense, all though I really wanted those extra .4 of a mile.I will just have work harder.

Erik

 

I was well beyond the rapid updating FCD close to 340 miles. I will watch to see if it will do it again.

Erik

 

Exactly what they said, I've had it happen with a few hundred miles on the tank and the car just sitting in the garage overnight.

 

It's crushing when you have to work for your entire commute just to get back to the MPG you had when you pulled in the night before. Sucks.

 

To make matters worse I have built my MGP upto 53.7 and for the last 3 days I have been driving almost nothing but city, and down the MPG goes.