Riding high

Odometer: 18342.2
Tank Mileage: 686.1
Gallons Added: 16.419
Long-Term Average: 41.6
Short-Term Average: 41.6
Calculated Average: 41.7

Just a touch further than the last miles driven record. More exciting is a new tank mileage record. While I truncate the values in the summary, I do record them in a more detail personal log. My new record tank average is 41.79 mpg. This includes an Interstate trip to Dayton for the the weekend, running around base while there and my normal commute on either side.

There was one exceptional leg. I had to go into work early Monday morning after I drove home from Dayton. I averaged 54.7 mpg over 25 miles on the short route that minimizes Interstate travel. Having almost no other traffic and most traffic lights flashing yellow really helped.

The 3-tank and 5-tank averages were also records, but I don't have them handy at the moment.

New Miles Driven Record

Odometer: 17656.0
Tank Mileage: 685.1
Gallons Added: 16.524
Long-Term Average: 41.2
Short-Term Average: 41.2
Calculated Average: 41.4

I hit 0 Miles to "E" on my way home tonight. By the time I got to the station I planned to used, I had just over 685 miles on the tank. This is a bit better than the previous miles driven record of 680. Commensurate with this is the most gallons added. I hope I never find out the absolute usable capacity of the tank. Assuming that the tank will take 16 gallons when on "E" seems to be well supported. That 16 gallons easily gets me over 600 miles of range and frequently over 650. The initial estimate for the next tank was 700 Miles to "E" when I started the car after the fill.

This tank included driving in Chicago for the weekend and the trip home (over 200 Interstate miles), a round trip to Lansing (150 Interstate miles) and three days of my normal commute (120 Interstate and 30 City miles). One thing about my commute: I have a choice between the route that yields the best mileage and the route that uses the least gas. They are very close, but that is the split on the averages.

2010-08-11 1906 ETA: My 3-tank (41.09, first time over 41) and 5-tank (40.71, first time over 40) averages are also records.

Not what they seem

Odometer: 16970.9
Tank Mileage: 646.8
Gallons Added: 16.146
Long-Term Average: 40.7
Short-Term Average: 40.7
Calculated Average: 40.0

My wife was looking at the numbers I've recorded for the various average mileage and was confused as they weren't moving as she would expect them to. For example, the previous fill had an improvement in Long-Term average of .8 mpg over the fill before. This was supposed to be a "lifetime" average, but it had reset with the display about 9,000 miles ago. For this to make sense, the tank average would have to have exceeded the long-term average by about 10 mpg. Also, the short-term average should have moved further in response to the same input as it is supposed to show the average over the last 2000 miles. Instead, the two averages seem to run pretty close to each other. In fact, calculating backwards from the calculated tank mileage, the long-term and short-term mileages seem to have a weight equal to about 1600 miles. Allowing for the possible differences in fills and 2000 miles is in the ball park.

This is all minor, but, with both car-generated averages running so close, I'll probably start resetting the displayed average more often (possibly for each tank).

[Posted 2010-08-10]