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Snow....what an impact on MPG

Discussion in 'Prius v Fuel Economy' started by G Man v5, Mar 3, 2015.

  1. G Man v5

    G Man v5 Member

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    This may be old news to some, but as a new Prius owner, it was quite eye opening to me to discover the huge impact a bit of snow has on MPG.

    About an inch on the roof, combined with snow behind the mirrors, and plenty of snow built up in the wheel wells, my MPG on the hwy driving at 60mph dropped to 24mpg. Snow sucks!!
     
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    Were the roads clear? I'd think snow on the road's going to impact rolling resistance, even wet roads make a difference.

    It's best to brush snow off the roof, avoid it blowing off, blinding someone following you. Also, do take it easy: 60 mph in snow is freaky.

    BTW, I was out mowing the other day. :ROFLMAO:
     
    #2 Mendel Leisk, Mar 3, 2015
    Last edited: Mar 3, 2015
  3. css28

    css28 Senior Member

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    That's pretty extreme.

    Conditions permitting, I try to sweep as much off the car as possible when I'm setting out. I've seen mid 30's under similar conditions, with my hatchback.
     
  4. bisco

    bisco cookie crumbler

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    yes, the road friction is brutal on wet/slushy streets.
     
  5. Robert Holt

    Robert Holt Senior Member

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    The hard data I found in this was a Missouri road surface roughness pre-post study that found very small 1-2% differences using dump trucks as the test vehicles.
    BUT, anecdotally I have had big reductions in mpg due to rough, rutted, potholed gravel roads, which I attributed to increased rolling resistance (from 55 to high 40s, so more like a 10% or more decrease). Anyone else have data for gravel/dirt road mpg changes ??
     
  6. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

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    I agree. The last two winters here in Michigan have been pretty damn snowy. What I do to circumvent the huge mpg drops in the winter & plowing through the snow, I installed an engine block heater and I grill block 100%. If the wheelwells are caked with snow kicked up from the road, I stop at the $.25 car wash and get it out of there, as well as anywhere else on the Prius. I then go home, park the car in the garage and start out the next day fresh!
     
  7. G Man v5

    G Man v5 Member

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    The roads were clear at the time. A bit wet, but not snow covered.

    The snow on the top of the car was more "ice"....It was not the blowing kind, so no need to worry about me "blinding" other drivers. After 30 miles I did pull off, and then removed the remaining ice/snow from the roof, as well as the accumulation in the wheel wells.
     
    Mendel Leisk likes this.
  8. rdgrimes

    rdgrimes Senior Member

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    Snow on car: 10% of your drop in MPG.
    Cold temps: 90%.
     
  9. G Man v5

    G Man v5 Member

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    A 25 cent car wash still exists? Wow, you are livin' large!!
     
  10. Blizzard_Persona

    Blizzard_Persona Senior Member

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    Ice on your roof is as dangerous if not more dangerous than blowing snow! Every year there are deaths on the highway attributed to chunks of ice flying off of vehicles causing a wreck, either directly or indirectly.

    Def. Take the time to carefully break that ice off before you start on your trip pls.

    Yes the cold weather really kills our MPG. It sucks but what you can do is slow down, try 55mph as in bad weather you prob shouldn't be driving much faster than that anyways. Block your grill, pump your tires up a bit. I run 44/42 but that's a little high for most, try 40/38 for starters.

    Watch some YouTube vids on how to drive the prius for optimal mpg. Bob Nagy comes to mind. Learn to pulse and glide. Don't warm your car up for too long if at all if you can hack the cold. The higher you set your heater, the longer the gas engine will run and won't shut down thus burning more fuel...

    All the best.
     
    #10 Blizzard_Persona, Mar 4, 2015
    Last edited: Mar 4, 2015
  11. G Man v5

    G Man v5 Member

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    Ok, it wasn't pure ice....It was snow that was lightly hardened. And it was in no danger of "falling off".

    Again, that roads were clear of snow. Driving 60 was much lower than the prevailing speed of other traffic.

    The original post was about what I experienced with some snow on the roof and under the wheel wells. Perhaps I need to put disclaimers in future posts regarding the exact condition of everything so I will not be scolded from people making incorrect assumptions.
     
    #11 G Man v5, Mar 4, 2015
    Last edited: Mar 9, 2015
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  12. Blizzard_Persona

    Blizzard_Persona Senior Member

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    Oh and was that 24 mpg just for a short trip, for a longer extended highway drive, or for an entire tank?

    If it was just for a short trip it's nothing to worry about as the car never got up to temp.... When I make a quick few Minuit run run to town and back I can even score worse for mpg, goes for all of us in a cold climate with a prius.

    I don't think 24 mpg is even possible for an entire tank even driving one like a race car. Lol.

    Ok Sir, we are simply trying to help! In my last couple posts I gave you every tip I know to optimize mpg...

    Obviously my statement in reference to the icy/snow on your roof was a friendly (legal) reminder. Sorry for "scolding" you.. I'm quite sure most people that caused accidents by way of ice / snow flying off thier roof were "sure" that it was not going to fly off thier roof...

    Either way best of luck with your v. If you do everything I stated in my last post and still get 24mpg consistently maybe the dealership upsold you on the new Hellcat v? ;)
     
  13. rdgrimes

    rdgrimes Senior Member

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    Your own incorrect assumption was that the snow/ice stuck to the car had much to do with your low MPG.
     
  14. G Man v5

    G Man v5 Member

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    Hmm, incorrect assumption??? I think not. The snow and the ice had EVERYTHING to do with the low MPG.

    Immediately after removing the substance from the top of the car, as well as the wheel wells, the mpg instantly went from 24 to 39 for the duration of my trip. (10 miles) The car had been driven for approximately 30 miles before removing the snow.

    I've driven plenty in cold dry weather, where the MPG has NEVER been that low. Not even close. And I'm not having difficulties obtaining higher than the EPA estimates. So if some people feel the need to chime in that my assumption is incorrect, go ahead...if it makes you feel good.
     
    #14 G Man v5, Mar 5, 2015
    Last edited: Mar 9, 2015
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  15. css28

    css28 Senior Member

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    Don't underestimate the value of the aerodynamics of these vehicles (and the drag from having irregular snow on the roof)--I'm agreeing with G Man v5.

    You'll notice that the v takes a hit in highway mileage relative to the hatchback. A good part of that is the difference in its aerodynamic drag.
     
    #15 css28, Mar 5, 2015
    Last edited: Mar 5, 2015
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  16. Blizzard_Persona

    Blizzard_Persona Senior Member

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    So I suggested removing the snow and ice and you considered that "scolding". Lol.

    And removing the snow and ice totally solved your problem.

    We "chimed"in because you started a thread asking a question...

    -your welcome.

    :)
     
    #16 Blizzard_Persona, Mar 5, 2015
    Last edited: Mar 5, 2015
  17. mikefocke

    mikefocke Prius v Three 2012, Avalon 2011

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    Years ago I had a windshield taken out from ice/snow blowing off the cab of an 18 wheeler coming towards me on a 2 lane road. Entire windshield honeycombed with cracks. Since I was only 4 miles from the ski resort, we went skiing as intended, then drove back home with my head hanging out the window or crouched down peering through the 4 inch undamaged portion of the windshield corner while a passenger watched the side of the road. Scary.

    It isn't just the top of the car that gets inefficient in passing air, look at the sides of the car and see the accumulation of snow build up there that creates a rough surface.

    And even on a wet surface, your tire is pushing at that water and MPG suffers. Worse in snow.
     
  18. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

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    Lets not forget, that the little 1" air deflectors underneath the car, near the rear tires, affect Mpgs. There were a few members here that removed them and their mileage dropped!

    The Prius is very sensitive to factors that affect aerodynamics. Absolutely snow all over the car and in the wheelwells, or underneath the car do not allow the air to flow "smoothly".
     
  19. G Man v5

    G Man v5 Member

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    Wow, and the hits keep on coming....

    Blizzard Person........please tell me where I asked a question in my original post. Perhaps a refresher course in basic reading comprehension is needed. I did not ask a question, nor was I seeking advice. I was relaying my experiences. It was quite simple and straightforward.

    This is a perfect reason why many people stay away from boards...dealing with utter nonsense.
     
  20. mikefocke

    mikefocke Prius v Three 2012, Avalon 2011

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    It seems to me you drive down the road, you have your heater on. The metal on the top eventually gets slightly warm and then melts the underneath of the icy snow just enough to break the bond between the ice and the paint finish. The car hits a bump. The stuff is now able to break loose and air is pushing up and against it and it flies off. How does this not happen? And the faster you are driving, the more air is pushing against that stuff and the further it is going to fly and it doesn't necessarily stay in your lane as my experience cited above taught me.

    Thanks for posting your experience. I had not thought of the effects of some snow accumulation on the surface of the car affecting mileage until you posted.