It gets fairly cold in the winter here (east of Albany, NY). In fact, right now it's 2 degrees. I think gas is 10% ethanol year round here (except for high test, which is ethanol free). I'm wondering how much of a hit winter blend fuel has on fuel economy? I realize winter is not a good time for mpg's, regardless. The interwebs seem to indicate it is a factor. Thanks.
Hard to quantify just the fuel itself effect on winter driving in colder climes. As you’ve found from your interweb searches, lots of things working against us re: miles per gallon/liters per km (or km per liter) in the winter – the US winter blend fuel itself (higher Reid Vapor Pressure = more lighter fluid (butane) in it, overall lower density), higher air density with colder temps (more aerodynamic drag resistance), longer times getting engine temps up, more electrical loads from heated seats/defroster/etc. Somewhat surprising numbers on the outsized contribution of higher air density with colder ambient air temps to reduced fuel economy – it seems to be the biggest factor. And of course, highway driving vs. putting around town in sub-freezing temps, headwind vs. tailwind, etc. Fuel Economy in Cold Weather | Department of Energy Learn the facts: Cold weather effects on fuel efficiency Atmospheric Effects on Aerodynamic Drag Anecdotally @Hammersmith (N. Dakota) and @KMO (Finland) could probably share their observations on winter city vs. highway drives.
Different regions get different seasonal blends, so there isn't a single answer your question. Around here, all the usual octane ratings are E10. Customers wanting E0 must go to specialty outlets, such as marinas.
Not to be picky, but the original post recognized that winter wasn't a good time for fuel economy and asked specifically about winter blend fuel.
Here in south central Virginia, our family has seen winter blend fuel lower fuel economy on all our Toyota Hybrids. i currently see it with my 2025 Camry.\ and previously, with my 2017 Prius. E10 vs E15 has a big impact too. I only buy gas from a station that specifies E10 (up to 10% ethanol).
Winter blend in the US has an energy content about 3% lower than summer blend. An exact number depends on the specifics of the gas; octane, reformulated or not, ethanol content, etc, being compared.
Another factor is denser air coupled with longer warm-up times and slick pavements. An ICE car usually got better mileage in the rain - NOT our hybrids - that's how sensitive they are environmental conditions.
And everyone forgets to air-up their tires when the temps drop, so there's an extra mpg penalty hiding there. You can lose a surprising amount of mpg to underinflation before the pretty "low tire" lamp activates on the panel.
Sorry, should've stated more specifically, 'pre-ECU' cars. That's why they sold those water injectors kits to eak out a few extra mpgs back in the day along with those 'tornado' air swirl thingy-a-bobs.
My last tank was 53 so I guess I shouldn’t bitch. There was a 300 mile trip on the thruway at 65, which seemed to have dragged it down. But it’s been cold. Not Canada cold, but cold.
Yeah, I swap out my summer air for winter air every year. To save money I save the summer air to swap back in at spring time.
