MBWorld.org Forums - MPG -- summer vs. winter

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MPG -- summer vs. winter

All cars get a little worse MPG in the winter, at least all that I've owned.

My E550 has the biggest differential in any car I've owned. Summer MPG = 27; winter MPG = 22. I do have an "easy" commute of about 20 miles with just a few stop lights.

What is your experience with MPG summer vs. winter?
https://cimg3.ibsrv.net/gimg/www.mbw...fc57adf60f.jpg

same
actually less AC in winter should make better mpg but the difference is not measurable.

Mine might be 1 mpg worse in the summer due to heavy AC use (Florida). Considering it doesn't as cold here, I don't see a drop in winter.

Quote:

Originally Posted by ghlkal (Post 7367392)

Your mpg summer vs. winter is big difference because of the way you drive. To get the car to give you the best mpg it needs to have the engine and catalytic converters and oxygen sensors heated up. When you first start the car and go driving the car uses pre set curves for the fuel control. It is an open loop control and in most cases makes the engine run rich. This is why it is common to see the heavy exchaust at the start. When the needed components build up enough heat the system switches to closed loop control and adjust the fuel amount based on sensor readings.

The time it it takes to build enough heat to converters and oxygen sensors depends on the outside temperature and as your trip is only about 22 miles you may be driving half or more of it in open loop control, which really hurts mpg in stop-and-go traffic.

I've wondered if part of the reason for the reduced mileage in winter is the density of the air. Air is denser at lower air temps thus the engine must provide more gasoline to maintain the desired air/gas ratio. Result is at low temps, for each mile driven more gas is needed to mix with the increased air forced into the engine, The result is more HP but at the cost of lower MPG.

Quote:

Originally Posted by putter (Post 7367987)

No, colder air should not make difference assuming the mass air flow calculation is correct. You control the speed with the throttle so when you get more oxygen in the engine with the colder air you just need to open the throttle less. More power with the same throttle opening for sure. Very easily noticeable.

Don’t forget all fluids and greases are colder, and therefore thicker, during the winter. They take more power to move the parts, which takes fuel.
A warm day will put everything back to normal.

Quote:

Originally Posted by kbob999 (Post 7368203)

Don’t forget all fluids and greases are colder, and therefore thicker, during the winter. They take more power to move the parts, which takes fuel.
A warm day will put everything back to normal.

Or long drive.
For some time my wife was driving wagon 1.5 miles to her work place. Even in CA summer the car was making 7 mpg on those runs.

Yep, I know why the MPG is lower in winter.

Does anyone else experience a 20% differential in MPG between summer and winter? In my other car's it's about 10%

Check your Tire Pressure. Most tires will drop 5 lbs at night in cold weather below 15 degrees! I keep mine at 35psi when cold. They go to about 40psi when driving distances on expressway or a short 5o mile trip going 55-60mph. I averaged 26.3 tonight average temp was 22degrees for 98 miles. I have a 2010 E350 fully loaded! I also have Michelin Ice-Xi3 Blizzak Snow radials.