I work with statistics at my day job and I wish my usual data sources were as forthcoming as you are :lol:. Interesting split of numbers. With regard to the winter mileage rise, is there any sort of seasonal fuel reformulation that may affect that? One would think that a rise in urban driving and fighting the increased resistance of a snowy road would counteract any gains from cold air-based improvements in mileage.
Oh look, math has invaded this tread too
Yeah, math tends to do that. It's sneaky.
There are plentiful reasons for increased consumption during the winter (unless compared to a summer that needs a lot of AC).
* Actual Snow and Ice: Slower urban speeds meaning lower gears and more engine friction, increased rolling resistance, more complicated parking (the streets around here tend to become inverted train tracks - two furrows where the weels go and ice between/outside them, many lesser drivers even fail to park alltogether)
* Temperatures: More cold running for the engine, heated seats, heated windows, heated mirrors
* Tyres: Grippy on snow and ice means more friction on recular pavement
* Laziness: If it's cold and
outside there is a tendency to swap bicycle for car, resulting in some additional shorter trips
* It's Just Not Summer: Going to Denmark or other recreational spots around here tends to be good on fuel, not much of that in the winter
( * For other drivers: Letting the car idle itself warm to get rid of snow and ice on it, will ruin any mileage figures. I like snow and ice, hence no need to do that. Also, I don't see the point in punishing your engine with extra-long cold running time. Start, get out of the parking spot, set off at low revs with medium load. It'll get warm in no time. Idling = no load = little fuel = little heat = great pain for the poor engine.)
As for different fuels, we have three types of 95 petrol: Winter, Sumer, Inbetween. Here's the "rough" specification:
https://docs.google.com/document/d/1bJ3k506aLQkKYNmZI33a-GMvUqwc0uIadUMOAJvG9Aw/edit?hl=en_US
The major difference is the way it boils (see graph, red is summer petrol and blue is winter petrol) and its dry vapour pressure equivalent. Simply put, they use more isopentane and butane in the winter to aid cold starts - more fuel vaporizes at lower temperatures. No idea whether it affects consumption.
https://pic.armedcats.net/n/na/narf/2011/08/04/500px-Siedekurven_white.svg.png
Cold air,
if my charged and intercooled car notices much of that.