On my 2005 HAH, sometimes the navi mileage is about 5 MPG low (relative to both manual calculation and the instrument cluster). I've had no software update (that I know of).

I've only observed this twice, so I'm not positive of the conditions. I think it happens when the initial mileage on the tank is actually low (stop & go). I've never seen this happen when the first few miles are on the open road and the mileage is actually high.

Anyone else observed anything like this?

AB in SJ