I noticed that the air temperature has a large effect on fuel 'mileage'.
Middle of winter in Toronto around town ~8.4 L, I have not driven on the highway in the CRZ in the winter. (use the Volvo).
Summer temps. 7.2 L in town, 5.1 L on highway at ~ 105 kph.
Tyre pressure too. mileage bad at 28 psi, good at 35 psi.