Mileage, 2000 - 2006

I dug another one of my gas mileage notepads out of my glove compartment. This one covered 10/1/2000 through 11/7/2003, which is where my previous charts picked up. So I added the older data to the spreadsheet I made the other day and more than doubled the number of data points.

1996 Toyota Tercel fuel economy
(miles per gallon)
10/1/2000 - 4/23/2006

The vertical black lines indicate December 1, and the vertical blue lines indicate June 1. I have placed labels for each year centered on the June 1 mark (with the exceptions of 2006, which is placed on the extreme right of the chart, and 2000, which is not labeled but is represented by all the points to the left of the first vertical black line.) By expanding the y-axis to concentrate the data in the middle third of the chart the sinusoidal nature of my gas mileage becomes pretty clear, reaching a peak in mid-Summer and a minimum in mid-Winter. Keep in mind that my driving habits do not vary significantly throughout the year: each workweek I put on at least 333 miles (5 x 66.6 miles). I take several long trips in the Summer, but do a lot of long trips in the Winter, too, especially around Christmas. Note the interesting lack of data points above 37 or 38 mpg in the Summer of 2004. I wonder what brought that on?

Price per gallon of gas
(in dollars)

One interesting feature comes out of the expanded price-per-gallon data: notice the dip down towards $1.00/gallon, a price not seen since the heady* days of the Clinton administration. Looking at the data shows that the drop began around 10/15/2001 (when gas fell below $1.30/gallon), reached a minimum on 12/12/2001 (when it hit $1.039/gallon), and ended around 3/23/2002 (when it rose above $1.30/gallon, never to return.**) This was a five-month period starting one month after the September 11, 2001 attacks.

I still have another six years of notebooks floating around somewhere, including another four-and-a-half years of data for this car. But I'm really interested in knowing if anybody else has been keeping records of this sort?

*Heh heh, heh heh.
**That's not true. Prices dropped below $1.30/gallon on 11/22/2002 - way below, down to $1.249/gallon. Prices rose above $1.299 again with the 12/19/2002 fill-up, up to $1.459/gallon. Then they never dropped below $1.30/gallon again.