Absolutely dismal MPG...

Discussion in 'Gen 2 Prius Main Forum' started by SW03ES, Dec 5, 2007.

  1. SW03ES

    SW03ES Senior Member

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    We drove the Prius today in the snow (its better in the snow than the Lexus) and I noticed how terrible the MPG had become...get this...26.6. Thats got to be some of the worst mileage I've ever seen reported on here.

    Any ideas? Its cold but its not that cold. My fiance drives a very short commute to work but still....
     
  2. TheForce

    TheForce Ron Paul 2012

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    Was there a lot of slow stop and go driving with the heat on? This will cause the mpg to drop. I remember last year we had a quick snow fall and I was stuck in traffic for about 2 hours. dropped my mpg from about 55 to 45. But I also did not have the heat on or anything.
     
  3. Stev0

    Stev0 Honorary Hong Kong Cavalier

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    OK, everybody in unison, on the count of three!

    1-2-3:

    COLD WEATHER PLUS SHORT TRIPS = BAD MPG.

    Anything below 35 can be considered cold.
     
  4. Bob64

    Bob64 Sapphire of the Blue Sky

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    winter actually gets ya in 4 ways:

    winter gas
    heater = on (unless your wearing layers)
    stuck in stage 3/3a (unless its a long trip)
    lower tire psi


    Anyway, first, winter gas has less energy, so the car has to use more of it to do the same work.

    turning on the heater robs the valuable heat from the engine, forcing it to drop out of stage 4 (if you manage to get into stage 4) when the coolant temps drops below.... 70C or so. Believe me when I say the heater makes it drop FAST. A minute and it'll drop it from 80 to 68C... depending on how high you turn up the heat of course...

    stuck in stage 3/3a, due to the cold temps, the coolant does not reach 70C easily. In addition to the heater being on, you may remain stuck in stage 3 for the majority of your trip. (symptoms of stage 3: engine on at speeds below 35mph unless stopped)

    and finally, cold air reduces air pressure inside your tires... thus you need more of it to maintain a high tire pressure. (low tire pressure increases rolling resistance)

    And for the record, depending on the traffic, a good hypermiling run for me in traffic will yield about 55mpg in the wintertime as opposed to my record of 75mpg during the summer time. However, a bad trip (huge congestion, traffic, barely crawling along) for me will be about 40mpg.

    If you find yourself in really bad traffic, I suggest the following:
    Avoid turning on the headlights (unless it is snowing or is dark)
    turn off the audio/radio/cdplayer
    turn off or reduce the mfd brightness
    turn off the sks
    avoid turning on the heater except to defrost the windows.
    Try to get into stage 4 mode. (stop for like 6 seconds if the engine is on, and hopefully it is 70C or higher and will then enter stage 4...)

    The point of these measures is to conserve the hybrid battery as well as to avoid the engine turning on to remain warm.
    I will also recommend blocking your grill (at your own risk!) in these conditions.
     
  5. Tideland Prius

    Tideland Prius Moderator of the North
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    do not know but it snowed over the weekend and crawling along with traffic (cause we're not used to the snow), I got my worst mileage ever on the MFD - 8.0L/100km :eek: (that's 29mpg!!)
     
  6. galaxee

    galaxee mostly benevolent

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    you don't wanna know what my hellacious commute alone gets me... add in cold and heater and winter gas up there by you and that's a big hit.

    what kinda commute are we talking here? and did you just fill up or reset the mfd before the trip?
     
  7. Schnauzermom

    Schnauzermom New Member

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    But you'll know if your tire psi is low, because you'll have that bright red symbol aglow on the dash.
    Mine scared the crap out of me the first night I was out late and the temp dropped. Yeah, they were all a tiny bit low - by no means anywhere near flat.

    I'm just not used to warning lights for potential problems or routine maintenance. In my Prism, lights were "idiot lights" that only came on if there was a huge problem, like the death of the catalytic converter, or the time Firestone failed to tighten the oil plug after changing the oil and I wound up over 2 quarts low.
     
  8. Tideland Prius

    Tideland Prius Moderator of the North
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    SW has an 04 so it doesn't have a TPMS.
     
  9. Boo

    Boo Boola Boola Member

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    It's the Tire Pressure Monitoring System. It's a major safety feature. Underinflation is dangerous. The TPMS alerts you when the pressure of any tire drops 25% below its registered setting.
     
  10. SW03ES

    SW03ES Senior Member

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    Yep, '04 no TPMS.

    I'd agree with you if this were just an isolated occurance, but we've been getting bad mileage for a while now. 26.6 is a new low (the tank has about 50 miles on it) but we've regularly seen it at 29. I don't think we saw 40 at all this summer. We used to get much better mileage.

    Its a pretty short commute, maybe 3 miles. Even when it gets driven more normally though the mileage is not as good as it used to be.

    The tires are good Michelin MXV4s aired properly, I check tire pressure weekly.
     
  11. Rae Vynn

    Rae Vynn Artist In Residence

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    Just to put it in perspective... what kind of MPG did you get with your previous vehicle in this sort of weather?

    Even now, I'm getting an easy double MPG over my previous vehicle in the same conditions. Plus, the Prius handles so incredibly well in our torrential rains (with Hydroedge tires on it), and I feel much safer driving the Prius.
     
  12. Bob64

    Bob64 Sapphire of the Blue Sky

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    3 miles is your problem. on ANY car, the first few minutes will always get you bad gas mileage.

    Try taking it for a longer commute and see if your mileage improves. If it still doesn't improve, then you might wanna start checking something...

    If your really paranoid about your low mileage, you can also buy a scangauge (pricey item ~150$) to see exactly why. With it you can check if the engine is running all the time, what the coolant temps are, and other data like current trip mpg.
     
  13. clayton4115

    clayton4115 Junior Member

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    3 miles is way to short, you need atleast 10 miles for the car to warm up

    people plz dont come on here complaining about poor FE if your drive is less than 10miles, anything over 20 miles is the ideal drive !
     
  14. Schnauzermom

    Schnauzermom New Member

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    Tom, none of them were 25% low - each 3 or 4 lbs low, which is more like 15%, based on the owners manual recommendations. Maybe it was because all of them were a little low?

    The temperature had dropped about 25 degrees over the late afternoon/evening, as I was parked outside at the dog agility school. I checked them and decided I wasn't going to break out the air pump in the cold and dark, out in the country, with coyotes howling and freaking the dogs out. As soon as I got her home to the warm garage, I carefully inflated them to the exact specifications (different for back tires than for front) and haven't had any more trouble.
     
  15. Schnauzermom

    Schnauzermom New Member

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    Amen! Any time I get upset over "low" milage, I remind myself that the Prism got 28mpg on a good day.
     
  16. F8L

    F8L Protecting Habitat & AG Lands

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    SW03ES has been on the forums for awhile so I'm sure he is aware of the issues with cold temps and low milage commutes. I think he may have just been so shocked with 26mpg that he forgot. :) He's definately not a newbie.

    ES, can you go take a longer drive and see how the milage measures up or use Jimbo's technique of reseting the MFD before and then after initial warm up? This would help determine if there is a problem with the car or you commute/driving.

    You should see roughly 25mpg before warmup and 40+ after.
     
  17. jayman

    jayman Senior Member

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    At -40, stuck in stop-and-inch traffic, with no winter front and Max heat, I was getting about what you did. My previous vehicle, a 2000 GMC Sierra, usually averaged under 7 MPG for the same driving conditions

    My Dad used to have a 2003 Buick LeSabre. Actually a fine car, reliable and fairly decent fuel economy for the size. It got around 12 mpg similar conditions.

    What really helped my fuel economy was making the winter front. In similar conditions I can usually get 38-40 mpg
     
  18. Mawcawfee

    Mawcawfee Prius-less (for now)

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    Hmm. I drive a '99 Prizm now. LSI, 5-speed, 110K miles. I routinely get 25+ city / 35-40 hwy. But I drive with a light foot, so the saying YMMV certainly applies. Cheers!

    <edit> ... but 25 mpg is if/when I drive it like I stole it, which is not often. ;) 35 mpg overall avg is typical. </edit>
     
  19. daniel

    daniel Cat Lovers Against the Bomb

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    This is low indeed. My first winter (January 2004) I allowed the car to pre-heat for 5 minutes because at 20 degrees below zero F. I just cannot sit in an unheated car. I then had a 10-minute commute, with the heater full blast, and seldom got into S4 operation unless I hit a red light near the end of my commute, and even then the engine didn't shut off unless I turned off the heater at the stoplight. I was getting 29 mpg. But as someone else commented above, the first 5 minutes is even worse, so a shorter commute than I had would get even lower mpg.

    Except for stopping for 6 seconds to get into S4 operation after the engine is warm enough, the above are dreadful ideas, and I recommend very strongly you not employ them.

    Headlights are a safety feature: They make your car more visible to other drivers. You do not want to make your car less visible! And the headlights do not consume much energy!

    The stereo, MFD brightness, and SKS have negligible effect on mpg. Maybe using them all for ten years would consume an extra ounce of fuel!

    Keeping the heater off just to gain one or two mpg is anal in the extreme. A 3-mile commute at 25 mpg uses 0.12 gallon of gas. If leaving the heater off raised your mpg to 30 mpg (and it's unlikely to have that much of an effect!) your commute would use 0.1 gallon, saving you 0.02 gallon, or 2.56 ounces of gas. And the "price" you would be paying to be able to claim 30 mpg instead of 25 mpg is frozen buns, frozen toes, frozen fingers, and probably end up catching cold and missing a week's work.

    With a commute that short, in very cold weather, you're going to register very low MPG. But because of the short driving distance, that low MPG still results in burning very very little gas. Instead of obsessing over the mpg numbers, we should be looking at gallons of gas burned per year, and by that measure, you are one of the real champions!
     
  20. FishHawk

    FishHawk New Member

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    I don't know how some of you got great mileage.

    For me the best I get in warm weather is about 50mpg. Yes , I know how to pulse and glide but the claims of 55 to 60mpg is rather hard to believe. I'm talking here about long trips not short runs of 5 or 8 miles. I've pumped up the tires and done all of the tricks but I can't seem to get a tank that averages 55mpg. That being said 50 mpg is not too shabby.
    In the Winter I drop to around 43 to 45 mpg still pretty good.
    FishHawk
     
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