I have been keeping track of my gas mileage when I fill up at the pump. I write down how many km's I've traveled on that tank. I always stop filling at the first click of the gas pump.

Using that data for the past year I've come up with this chart. I picked up the vehicle at the end of August 2009 but the first data points are mid way through September so I missed the first two tanks of gas.

I also grabbed a dataset of the average temperature at the Toronto Airport and graphed that on the right Y axis to see if temperature plays a big role in fuel consumption. Currently my gut feeling is that summer has more road trips which means more highway miles and therefore better fuel consumption. I also run on winter tires roughly when the temperature falls below 7C.

A few more summer/winter cycles will provide a better pattern.

Current combined gas mileage for the life of the vehicle is the green dotted line at 10.98 L/100km.

I drive mostly city but do have some 80km/h stretches of my commute.

Sorry the forum attachment manager shrunk the image - it should still be readable though.