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Mountains and Fuel Economy

Discussion in 'Gen 4 Prius Fuel Economy' started by axle2152, Aug 28, 2016.

  1. axle2152

    axle2152 Active Member

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    I live in the Blue Ridge mountains and there's a pretty big mountain between where I live and another town. The speed limit is 55 and there are grades between 7-9% without about 1,500 feet of elevation change. I was able to average between 52 and 55 MPG.

    For those who live in flat regions and are curious about what the hybrid system does when the HV battery is fully charged. The regenerative braking will stop charging the battery and the normal brakes will engage. The ICE will engage to assist with slowing the car down. I you use 'B' on a descent once the HV battery is charged the RPM's will go up a good bit.

    When you come out of a descent the system will prefer to use the battery even while applying a good bit to the throttle. So you can glide for several miles under the right conditions. While climbing the mountain the car seems to do a pretty good job, you do of course consume a lot of gas in the climb so if your range is 100 miles expect about 1/3 if you're doing nothing but climbing up mountains, because you go from using a lot of gas to using none you don't want to be low on gas.

    Anyway, this 2016 is by far the best especially comparing to the Prius C I had.

    What has been your experience with mountains? Kind of curious about the Rockies...
     
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  2. bisco

    bisco cookie crumbler

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    what a great spot for the pip!
     
  3. Coast Cruiser

    Coast Cruiser Senior Member

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    Nice report. Thanks. Nothing wrong with 55 MPG! :)
     
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  4. axle2152

    axle2152 Active Member

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    I'm not familiar with the behavior of the plug in Prius but I'm thinking the EV is depleted at first... I would also venture to say that the battery would be depleted very quickly on 6-9% grades at 55-60 MPH. I would expect similar economy overall. On the flats, yeah definitely a win for the plug in.

    No not at all. I think on a constant uphill grade the cruise control might actually do slightly better at maintaining speed and economy but it would be splitting hairs.

    Normally here in the area I can achieve between 62-75 MPG, the drive back from work when the AC is running nearly full blast, ICE warm up and the drive being slightly more uphill on the 19 mile drive, I lose about 10-15 MPG (but on the way I have achieved a maximum, so far, of 78).

    Car definitely has adequate power. I nailed it for a bit and the car probably could have done over 80 MPH going up the thing. So I think passing a semi might be possible on an incline as I often do meet semi trucks on that mountain and they're moving sometimes 25-30 MPH.
     
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  5. bisco

    bisco cookie crumbler

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    you can choose when to use ev, so if you know the area, you can use gas and just enough ev going up, to fully recharge the battery coming down.
     
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  6. axle2152

    axle2152 Active Member

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    That would make a big difference then. I will say going east you could likely fill the EV battery from near empty, not sure if the regenerative braking is more aggressive or charges faster than on the regular Prius, but I can full charge the HV battery from 2 bars and still have several miles on downhill. The only problem is it takes more braking force to keep the car from speeding off...you'd be going 80 MPH if you only relied on degenerative braking. I may have done the math wrong but if I go by what the trip monitor shows (30 Wh on the graph) I regenerated about 180 Wh which should equate to about 10 kW...in one minute... Seems a bit high but then again the battery moves up pretty quickly. I think I read somewhere that the regeneration maximum is 27 kW... Anyway, I probably butchered all that.

    Basically the same things that Prius C did this Prius does, but way more refined... Then again it isn't quite a fair match up between the two variants either. Prius C is an excellent car, as long as size isn't an issue for you...it became an issue for me... all of which doesn't apply to the thread lol
     
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  7. PaulDM

    PaulDM Active Member

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    I was getting 66mpg average across North Yorkshire Dales - UK (1500ft) and Pennines 1:20 1:17 rises / drops. Charging system often went into 'dump' mode due to 100% battery charge on downward hills in B mode
    2016 model d performed MUCH better than my previous 2007 model b which found those hills a challenge.
     
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  8. Kremtok

    Kremtok Smug Alert!

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    Driving between Anchorage and Homer I've gotten between 57 and 65 mpg. Distance is about 220 miles and it's all up and down through mountains. Highest speed limit is 65 mph, but it's mostly 55 mph. I just set the DRCC at the speed limit and relax, so the variation in mpg numbers is probably due to who and what are inside the car.
     
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  9. Mendel Leisk

    Mendel Leisk Senior Member

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    Probably best to get into B beforehand, while the battery's still filling. Coming down a local mountain I'll shift into B on the steeper sections, back to D when it gets more level, and at switchbacks. It's still full-to-the-gills by the bottom, but it must help.
     
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  10. midwesterner

    midwesterner New Member

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    I live in a flat area, though I get a lot of miles all over the country when I do long road trips - once or twice per year if I can. But I am very new to driving a Prius - have had my first for 2 weeks. So I'm a bit concerned about mountains as I'm not used to the Prius and how it handles slick conditions and steep grades.

    Strictly on mileage, I've been getting around 61 mpg on average (2016 Prius Two Eco) in Iowa. But also, keep in mind that Iowa is one of the most hilly states, despite having a reputation for being flat. The difference is that we have constant changes rather than long periods of ups and downs. And most of our grades are not as steep.

    I've been watching my information screens as I go up and down hills, particularly since I live in western IA on the eastern side of the Loess Hills and regularly travel to Nebraska, going over the hills to get there. I've had 2 1/2 such trips (I bought the car in NE) and for some reason, the route I take gives me better mileage one-way than the other (possibly wind?). When I picked up the car, it showed around 72 mpg and almost 250 miles. When I got it home, it was at 69 mpg. But within a week, it was down to around 61 and has stayed for another week. I don't know how the mileage was so good beforehand, but as a new Prius driver, I find it hard to be disciplined and give it as much gas as I should when it needs to turn over to the gas motor.

    Anyway, as far as mountains go, I would imagine that it depends on where you start and where you finish, as well as how full your battery is at the time. It would make sense that if you start at the bottom with a full battery, you use both gas and battery as you climb... then you charge battery again heading down and show a decent average mpg. On the other hand, if you start at the top with a full battery, you don't get the charging gain when heading down.

    That is my guess, but I'm a total newbie. I'm interested in what others say. I'll also be interested to know how others handle snow covered mountains. My last car was a 2009 Toyota Yaris, and I took it over Wolf Creek Pass once in late December, at night. I'm not going to say it was easy or fun, but I didn't go off the mountain and die despite that most would not take such a light weight vehicle with 15 in wheels over that mountain with snow... but I know a gas only engine works differently. With the Yaris, I used low gear to control speed on the downhill side in snow with minimal sliding... and I didn't use snow chains or cables. I am thinking I should invest in a set of snow chains before doing anything like that with the Prius.
     
  11. Rangerdavid

    Rangerdavid Senior Member

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    I live in Boone. Lots of mountains here. My office is a 2 mile, 1400 descent and then the same reverse climb back up to go home. I get a full charge going down, and in my 2016 3 Touring i get about 16 mpg going up to get home. In my 2006 Prius i only got about 7 mpg going home.


    Posted via the PriusChat mobile app.
     
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  12. axle2152

    axle2152 Active Member

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    That must be very very steep. I mean I was up in the Cherohala Skyway this past weekend and at worst I would be getting in the 20's

    I've been very surprised on the gas mileage, even when you nail the gas can still average 60 on a trip. I have yet to drive it on the interstate for any length of time but will be at the end of the month.
     
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  13. dangrass

    dangrass Junior Member

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    Just drove from the SF Bay area to 5,000 ft. in the Sierra and back. 55 MPG up and 67 down. Got a little lucky with the lack of headwinds on the way back over Altamont Pass, but on the other hand there was a lot of rain and water on the ground.
     
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  14. axle2152

    axle2152 Active Member

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    Well if it is a long descent probably won't matter regenerative braking charges quite fast on the gen4 compared to the Prius C I once had. I am sure that it is not possible for the engine to reach unsafe speeds. My thinking is to use the friction brakes as little as possible, very easy to overheat the brakes on long curvy descents.

    If you use it early you'll likely be using it the entire time too...Just depends on where you're at. Does seem the RPM's pretty much stay the same until you get under 30 MPH or over 65 MPH...The ICE will sping even in D when going downhill with a full HV battery (just not as fast)
     
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  15. MichelleStone

    MichelleStone Senior Member

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    I live in the Sierra foothills near Yosemite National Park. My home is at 2200 feet. I go up and I go down... up and down... every where I go. I did make a trip out to the Bay Area a few weeks ago... down the mountain, across the valley, over the Altamont pass. That trip gave me my best mileage to date at 67.5. I've got over 1200 miles on the car and the lifetime average on the display is 61.4. My normal driving comes in a little higher. I make an 80 mile trip once a month across the hills to get groceries and that's my worst at 56 MPG. I use cruise control most of the time and lately I've had the car in Power mode which gives me the same fuel efficiency. I have yet to drive up to the park to see what my mileage would be. That is a good climb and I'm sure it wouldn't be as good.

    I was very concerned to get the car. I didn't know anyone near where I live. I wasn't sure that the hybrid way of doing things would work under these conditions. It seemed as though it was fine tuned for flat city driving. But I took a chance and I'm very happy that finally, I've made a good choice in a car purchase.
     
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  16. RCO

    RCO Senior Member

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    I hope I shall do as well as Michelle, although I love almost at the top of a hill. To get from here to the city there are five hills to go up and down on route.

    My Rover diesel used to average 39 mpg
    Mercedes C200 used to average 41 mpg
    Nissan X Trail 2 litre diesel got 42 mpg
    Honda CRV 2 litre petrol getting average 32 mpg

    Now you know another reason I'm impatient for my new Prius! :D:D:D
     
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  17. MichelleStone

    MichelleStone Senior Member

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    I live up on a hill as well. I've tried to climb it on battery power, I've tried it at various speeds, I've tried pushing the car up ;) It's a pretty steep climb. I try to keep enough charge to come in on my gravel drive on EV alone. I can usually do that. When I leave though, I can go a very long way on battery power. I can coast down the hill for the first .7 miles. Then when I get on the highway, I can time it so I can get up to 55 MPH on battery power. That gets me 2 miles away before the next hill and that's where the engine kicks in. The thing I like about this car is that I can run on battery power. It's really quiet and I like that in my woodsy neck of the planet. I wanted an electric car but I couldn't afford one and it wouldn't really make sense to have one here where I live because I'm so far away from everything. The car is telling me that I'm getting anywhere between 22 and 36 percent of my driving on battery power. It is so cool.
     
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  18. fuzzy1

    fuzzy1 Senior Member

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    Are those figured with U.S. or Imperial gallons?

    From common U.S. fuel hog viewpoints, those numbers are excellent! You'd have no strong reason to switch to a Prius.
     
  19. RCO

    RCO Senior Member

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    Sorry, they're imperial and I would expect to increase my mpg to ~60 mpg with the Prius. All in all halving my fuel cost and that's very significant over here. At the pump prices have increased by up to 4% in the past week!
     
  20. Tideland Prius

    Tideland Prius Moderator of the North
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    Converted to US mpg...

    Rover: 33 mpg
    C200: 34 mpg
    X-Trail 2.0D: 35 mpg
    CR-V 2.0 gas: 27 mpg
     
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