I'm kinda new to driving and was wondering what kind of penalty I can expect in extremely cold weather(-20c sustained)? Drives are typically 15mins or less. I replaced my lower intake manifold gasket and though performance has returned fuel economy has slightly dropped. It's only been a 1/2 tank though and since i did the repair it's been at least -15c every day. I'd like to hear your thoughts or observations on mileage in the cold.