You did say that you were on your first tankful, after every fill, whether fill-up or partial, the mpg resets itself. I noticed the trip computer overstates my 2006 GS300 mpg reading by about 1.5 mpg. This is odd because my toyota Avalon trip computer states the mpg used on the Avalon exactly.
I would like to be able to adjust my mpg, but don't think I can, also I would like to keep a running tally of global mpg for the car's lifetime, but again it is not possible...... I do not believe the Japanese mindset is as keen on statistics as the American thinking, for instance in sports we only talk in statistics, not goals only.......
I am curious too, is there any way to get more ambient lighting in my GS300 cabin whenever I open the door, the miniature glow lights are cool but make it difficult to see anything, I need a flashlight to find an accidentally dropped item, or to read directions previously jotted on a piece of paper. The Avalon on the other hand lights up like a concert hall....