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Today there is a snowstorm in Finland, during which I noticed that slow speed driving might require pressing the accelerator somewhat more. This made me think whether driving on thick snow reduces fuel economy so much at higher speeds that the effect is noticeable.

So, does thick snow reduce fuel economy, and by how much? For example, if you have driven a long trip on clear roads and another long trip on thick snow, by how much did the fuel economy decrease?

Of course, when averaged over the entire year the effect is likely negligible, as the roads are plowed quite soon. It is probably the case that the effect of cold weather averaged over the entire year is bigger than the effect of thick snow.

  • High speed driving in snow? We don't do that where I'm from as it's dangerous. What make, model, year are you trying to repair? – cory Feb 22 '17 at 18:28
  • I can see an approx 200km difference on a tankful when there is snow and I'm in Switzerland i.e. 450 instead of 650... – Solar Mike Feb 22 '17 at 21:11
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    A good general theory question, which is certainly within the scope of this site. – cdunn Feb 22 '17 at 22:09
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    @cory: in Finland, it's not uncommon to drive on studded tires. There's snow on the ground for 6 months at a time. – Hobbes Feb 23 '17 at 8:00
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Driving through snow of any thickness is increasing the rolling resistance of the vehicle, meaning you will need to use more engine power just to maintain your speed.

Since there's no such thing as a free lunch, more engine power requires more air and fuel, which you are observing as more throttle required.

How much fuel will be consumed is affected by:

  • the amount of throttle you are using
  • the engine RPMs
  • air pressure and temperature
  • the load on the engine

Driving through thick snow increases throttle and load, so yeah, you will have worse fuel economy driving like this. How much snow, and what type of snow will affect how much more fuel you will use.

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