Why does car mileage (mpg) decrease in the winter or colder weather?
November 9, 2009 in Maintenance & Repairs
Did you know that you can save fuel and run your car on water
calvin_0416 asked:
Why does it take more gas to run cars in the winter time? Cars seem to lose 5-8 miles per gallon in the winter season so u lose fuel efficiency.
Did you know that you can save fuel and run your car on water
colder weather makes the engine work harder, uses more gas.
The gas that is used is different than in winter time. It is
designed to lower emissions. It is less efficient, you’re
not imagining things. It is a tangible difference as well
as it is a deliberate change by the US Government.
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warm ups, wet and icy conditions cause slower speeds and lots of slippage
Has nothing to do with the car everything to do with the gasoline being sold at the pumps. During winter months they sale Oxygenated fuel which decreases gas mileage. Read about it here: To me its a governemtn gimmick. Put lots of additives in the fuel to reduce emissions but you gotta burn MORE of the fuel to go the same distance effectively putting out the same amount of pollutants into the air. I bet the oil industry had their hands in on this one.
It takes the engine longer to come up to operating temperature; all cars are most efficient at normal operating temperature. This is most noticeable on short stop-and-go trips. On longer trips, this won’t make an appeciable difference. My car actually gets slightly better mileage on longer trips in cold weather due to the denser cold air.
Some people warm their engines at idle on cold mornings. That wastes fuel and is hard on the engine as well.
When the streets are ice or snow covered, you tend to operate a a slower speed that is less efficient. The resistance caused by the snow and slush can also reduce fuel economy. Spinning wheels also wastes fuel and it can add up quickly.
As temps drop, the lubricants in the engine, transmission…all the way to the grease in the wheel bearings and CV joints thicken. It’s just going to take more energy to get things moving as usual.
Also, beyond the added energy draw placed by running more electrical loads as mentioned by others, the engine spends a longer time in warm-up mode when started – runs rich to provide adequate ignition/engine operation, as it is the vaporied fuel that burns. The colder the fuel/air charge, the lower the rate of vaporization of the fuel (winter gas blends also include distilates that vaporize at lower temps), and denser is the air which also requires more fuel to maintain a given air-fuel ratio.
well with science behind me, it takes less effort to conbust warmer fuel because it is at that point less dense and easier to vaporize. now as far as fuel effinciency, i have no figures, but your figures sound plausible. and anyone who work on cars know less fuel conbustion, more fuel consumption. but that’s an educated quest on my part, not a fact.
Well actually cars should run the same in the winter. Actually they might even run better because of the cold air. Cold air is good for cars, this is the entire point behind a cold air intake. More than likely you are getting worse gas mileage because of two reasons. The first being that you probably heat your car up in the winter and anytime when your car is running and sitting still it is getting 0 miles per gallon. Warming it up even 5 or 6 minutes a day (at the increased idle to keep it from stalling) will account for this “decrease” in gas mileage. Another reason is that most people don’t follow their manufacturers suggestion for oil viscosity in the winter. If you check your owners manual it will probably call for thinner oil in the winter for easier starts and quicker warm up. These two combined will probably account for your 5-8 mpg “decrease.”
Driving habits, people tend to leave their cars running to keep them warm. Friction from lubricants that thicken in cold weather, and last, but not least: gasoline additives. Butane is added to gasoline in winter to facilitate combustion when temps are expected to be below freezing for a long time. When the temp of the fuel exceeds +31 deg F the butane evaporates, leaving less fuel in the tank. Newer cars with sealed fuel systems burn the fumes, and on older cars it evaporates into the air.