I just went through the exercise of posting our first 17 tanks of gas to the DB, from manual calculations, for our RX. After reading the above posts, was not surprised that our overall mileage is less than indicated on the trip-info computer.

We are a little disappointed in the mileage we're getting -- penciled out at 21.1 mpg -- but I think the low total can be ascribed, at least in part, to my wife's short commute, about 5 miles, and that we've only been driving it since last fall, so the bulk of the miles were over the cold (or cool, at least, in the Willamette valley) season.

If the DB mixes car-reported mileage with hand-calculated, and one is significantly different from the other, it would be interesting, on a large data set (maybe the Prius crowd) to see the averages split out for the two modes...

On the other hand, if the object of the scrolling bar charts and all is just to remind you to drive thoughtfully and help you do better, then maybe it's accomplishing its goal and the absolute numbers don't matter so much. The wife readily agrees that it works that way for her.

Benton 7may08