MFD Problem

We have a 2008, Option 2 we are fighting Toyota about. Hope someone can shed light on the problem.....We drive all the time with the MFD on the Consumption Screen. For its initial 4,800 miles the Average MPG figure - which I watch constantly, trying to move it up a tenth, oh joy - changed gradually, a tenth at a time. All of a sudden one day, just driving along, the Avg. MPG readings went crazy, jumping, for example, from 99 MPG to 20 MPG to 75 MPG etc. etc., all within a few seconds. For several days it remained erratic, though not quite so wildly, then settled down to changing constantly by tenths every 30 seconds or so, whereas it used to take a couple of minutes or more to change by a tenth, regardless of speed, terrain, etc. Finally, it seemed 'normal' for a couple of weeks, then went nuts again for the second time. This time, at the "30 second" stage, we took it into local T dealer. (Also, occasionally the 'reset' button resets itself to zero, when we're nowhere near the screen - maybe or maybe not related).

T service put it on their computer and said nothing wrong, then manager drove it three miles, during which the MPG changed by tenths five or six times, which, he said, is normal. For 4,800 miles it NEVER changed that rapidly, let alone jumped from 86 to 15 to 12 to 68 etc. HELP! They're trying to tell us we're stupid at best, crazy at worst!!! Anyone else having this problem?

 

Thanks for the input. Jimbok....we have not hit the reset button. Also a bit of info we forgot that may support bgee42's answer. Before we left toyota my wife went back in and closed the car door the avg mpg went down .1......?????