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fuel economy going up and down hills

Discussion in 'Gen 3 Prius Fuel Economy' started by dk_brookdale, Nov 11, 2011.

  1. dk_brookdale

    dk_brookdale Junior Member

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    I'm a new member. I don't yet have a Prius. Wanted to check the experience of those that do and have hills to drive. I have about a 50 mile/day commute which involves going up and over elevation gain (from about 500 ft to about 2000 ft) to and from work. I'm concerned about Prius mileage under such conditions.

    So, what kind of mileage would I expect to get? I was thinking that when going uphill the Prius would get low mpg but then going downhill would get much better mpg. And that it would average out to be the same as if I was not driving any hills at all. Is this the case?

    Any response or insights would be helpful.:)
     
  2. sipnfuel

    sipnfuel New Member

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    On moderate to steep grades, when you go uphill, you can expect mileage around 40-20 mpg, sometimes even less if you are accelerating or going from a dead stop. This is normal and not a cause for concern.

    On downhills, if you do not need to use your brakes, you can get Infinite MPG to 65 mpg.

    If you have a super long downhill where you need to control your speed by downshifting, then you can expect not to gain the benefit downhill. Your overall mileage will suffer, but it can be no worse than a conventional vehicle, and most likely still 1.5x better (~40 mpg).

    Depending on how you drive, you can expect 38-55 mpg overall, worst case to best case.

    You can get better over time in knowing how to control your speed on downhills so you don't need to burn fuel, and how fast to take the uphills so you set up your downhill runs, etc.

    In the beginning I would just drive it normally. If you simply drive with a light foot I think you can get at least 45 mpg, including a penalty for downhill braking.
     
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  3. cwerdna

    cwerdna Senior Member

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    I can't speak to those elevation changes, but what's the reason to be "concerned"? What other currently sold as new fossil fuel burning car gets better mileage? You can see how the Prius does at Most fuel-efficient cars and Best & worst cars review, fuel-efficient vehicles.

    At least your commute is long so you won't be killed by the mileage penalty of short trips. Mtngal, I believe has a hilly commute. Perhaps look at her posts.
     
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  4. fuzzy1

    fuzzy1 Senior Member

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    Hills schmills. It will still do better than any other U.S-market gasoline or diesel car you can get, except for the original (not current) Honda Insight.
    Based on the experience of several of us, the uphill section should consume roughly 0.15 gallon extra, compared to otherwise similar conditions without a climb. A fully loaded car will consume more, an empty car with a lightweight driver should consume less. If you get 50 mpg on the flats, then you should get about 38 mpg on this twenty-five mile uphill section.

    Whether or not the downhill will save enough to average out depends mostly on the terrain profile, and somewhat on your skills, which will take practice. Best case would be a perfectly steady gentle descent (1.1% for your commute), in which case nearly all the climbing penalty should be easily recovered. The downhill section would be about 71 mpg, averaging 50 for the round trip.

    Worst case would be descending all that elevation steeply in four miles or less, recovering very little of the climbing penalty and getting no advantage for the remaining 21 flat miles. This would produce about 60 mpg for the downhill commute, averaging somewhat above 46 mpg for the round trip.

    Your route is likely somewhere in between these best and worst cases, and it may take a bit of practice to get the best available results on the downhill section. The car can handle the uphill section quite well without you trying to game things.
     
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  5. qbee42

    qbee42 My other car is a boat

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    I did better than 50 mpg with a fully loaded Gen II Prius driving through Vail pass, which tops out just short of 12,000 feet. Prius do fine going up and down.

    Tom
     
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  6. F8L

    F8L Protecting Habitat & AG Lands

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    My daily commute from 50ft. to 1200ft. will produce 55mpg average (57mpg best) if I drive 65mph or slower and glide whenever possible. If I just drive without a thought to mpg then it drops to about 48mpg-52mpg.

    Here is what my elevation map looks like (one way). Multiply elevation by 10.
    [​IMG]
     
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  7. Homermex

    Homermex Junior Member

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    Just bought a 2010 Prius. I travel from the high desert to Los Angeles mon thru Friday. Going down the cajon pass I get about 60 or more mpg. Coming up I get 40 to 45 mpg. Very happy with my Prius
     
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