According to FuelEconomy.gov, a regular gasoline-powered car sees its gas mileage drop by 12 percent when the temperature is 20 degrees, compared to a more pleasant temperature of 77 degrees. ... Hybrids can lose between 31 to 34 percent of their gas mileage during cold weather conditions.

Does cold weather affect mpg?

Cold weather and winter driving conditions can reduce your fuel economy significantly. Fuel economy tests show that, in city driving, a conventional gasoline car's gas mileage is roughly 15% lower at 20°F than it would be at 77°F. ... Their fuel economy can drop about 30% to 34% under these conditions.

What can cause a drop in mpg?