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Temperature and precipitation affect the inner workings of a vehicle and the actions of its driver, both of which have an impact on the mileage. In cold, snowy weather, the fuel economy during trips of less than 10 minutes in urban stop-and-go traffic can easily be 50 percent lower than during operation of the same vehicle in light traffic with warm weather and dry roads.

Auto components such as electric motors, engines, transmissions and the axles that drive the tires consume more energy at low temperatures, especially during start-up. Oil and other fluids become more viscous as temperatures drop, which means that more work - and thus fuel - is required to overcome friction in the drivetrain components. In addition, the initial rolling resistance of a tire is about 20 percent greater at zero degrees Fahrenheit than it is at 80 degrees F. This rolling resistance decreases as the vehicle starts to move, and in trips of a few miles the temperature rise - and its effect on mileage - is modest.