Speaking with a coworker this morning, I mentioned how I expect my mileage to start bottoming out with the coming winter. Then I said something about all cars being affected by colder temps. He flatly denied it. Unfortunately, I never trended my Buick Regal for an entire year. I only did the summer leading up to Priapus. I figure someone has that data though. It might be the temperatures or it might be the "winter gasoline." I'm not concerned with what causes it, I just want to be right. He also rejected the idea of tracking his mileage over the winter to see about his car.
I've had 36 cars and have tracked MPG in most of them since 1962. I lived in a northern climate (NY) until '68, mid-latitude until '90 (VA and UT). ALL cars get worse MPG when the temp goes into the 40's and below.
My Mercedes 190D got about 38 mpg on my commute to work in summer. Winter it got as low as 25 mpg depending on temperatures. Her it gets as cold as 20 below, but figures only count to 10 below 0 in degrees F. At 20 below it just didn't run at all!
