The issue is cold starts.
The issue is cold starts. Every time that an engine is started from cold, its temperature needs to be raised from ambient to 190 degrees. If it is 20 degrees out, you have to supply enough fuel to raise the temperature of 1000 pounds of metal 170 degrees. That is over a pint a start or a quart a day or gallons per tank. It is easy to lose 25 to 30% of your fuel mileage with short trips.