It looks like unseasonably cold temperatures in the Chicago area have impacted our 2013 Honda Civic's fuel economy. Last month we observed the lowest-recorded fill-up yet at 23.81 mpg, quite far from the highest 42.83 mpg rating we recorded in the summer.
As temperatures drop, gas mileage suffers and longer idling times from warming up in the morning ding mileage even more. November may have just ended, but that generally mild month was more January-like in terms of cold as we saw low temperatures nearing single digits and high temps in the mid-to-low 20s. The Civic's overall average after 14,500 miles only dropped .25 mpg, however.