'16 real MPG

Discussion in 'Gen 4 Prius Fuel Economy' started by DieselHybrid, Dec 31, 2015.

  1. krmcg

    krmcg Lowered Blizzard Pearl Beauty

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    That is the total of the four fillups
     
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  2. dorunron

    dorunron Senior Member

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    The only thing I will say is this. Kevin McG AKA krmcg | PriusChat is blessed to be averaging 66.1 in a NON Plug In Prius. Only serious hypermilers will get those kind of numbers in a Gen III or lower.

    Enjoy your new Gen IV, and yes I am jealous but I will not go buy a new one. I am still paying on the last new one I bought.
     
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  3. krmcg

    krmcg Lowered Blizzard Pearl Beauty

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    Thanks. For me, driving is like playing a video game. Always looking to get the most out of every trip. We have a hybrid Avalon which we use for our "road trips", so this new car sees only about 25% freeway driving. My 2008 (because of many long trips) had a lifetime average of 50.5 MPG for 123,000 miles. I hope that I can get that many years and miles on this one...
     
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  4. Tideland Prius

    Tideland Prius Moderator of the North
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    Summer can't come fast enough. We got 54mpg on the first day and after that, it rained and the temps dropped and we're in the high 40s.
     
  5. Blizzard_Persona

    Blizzard_Persona Senior Member

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    When do gas stations start getting non winter blend gas in the pumps nationally? Has to be soon right? With that change we should all start seeing better numbers...
     
  6. retired4999

    retired4999 Prius driver since 2005

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    60 to 80 degrees f will really help MPG!

    Enjoy!(y)
     
  7. JohnF

    JohnF Active Member

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    My 2006 Insight's average MPG display was "accurate" within 0.5% tank-to-tank for the 66,000 miles I owned it. At least WRT the odometer miles. I didn't measure distance traveled by using GPS data. I figure the slight variations were a measure of variances in gas pump calibration and tank filling.

    The average MPG reading on my 2011 Prius was consistently high by around 5% WRT odometer miles divided by gallons pumped. Constantly taking 1/10th of the reading, dividing it by 2, and subtracting that from the reading quickly became really annoying. I haven't run a tank through my 2016 Prius yet but from the posts here it looks as though it will be more of the same.

    I agree with you that people need to chill out, though I think what they need to chill about is the hopelessly nebulous concept of "real" mpg that a "typical" driver would get in "typical" conditions. Driving style and speeds, weather conditions, type of driving, loads carried all mean that mpg for any car is just a range of numbers. The EPA numbers are more precise but they use fixed conditions that may or may not resemble the conditions under which the vehicle is used. They are just one data point from which we try to extrapolate comparisons between different vehicles. So the comparisons are really only exactly relevant under the EPA conditions, and we just hope they have some crude relevance to all the other conditions under we would be using that car.
     
    #147 JohnF, Mar 10, 2016
    Last edited: Mar 10, 2016
  8. bwilson4web

    bwilson4web i3 and Prime

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    Well put:
    The original, GreenHybrid database recorded temperature, gas, and miles so I used it to analyze Gen-1 performance. It did not take long to realize where one lived and their life-style was a strong MPG determinant. Those in hilly, cold areas, short drives just barely broke 40 MPG. Others in flat, temperate, terrains with longer commutes did quite well.

    Early in our 2010 Prius ownership using the EPA and Fuelly, a bi-modal (i.e., double peaked) distribution soon emerged. Again, mileage was often determined by the driving profile and location.

    My interest has and remains in the Prius engineering characteristics. I use it to be on 'the high side' of normal driving. In one case, 1000 miles on a single tank. But I also know what happens at 100 mph. The key is finding out the optimum performance points and staying just on the cheap-side.

    Bob Wilson
     
    #148 bwilson4web, Mar 11, 2016
    Last edited: Mar 11, 2016
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  9. pakitt

    pakitt Senior Member

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    My Gen3 is consistently reporting about 6% less fuel consumption as calculated...
    The speedometer is up to 10% higher than actual GPS data.
    I really hope the new Prius will be more accurate...

    BTW: when I tested it last week with 0C, I got a fuel consumption, without any effort and not really looking at what I was doing while driving, all hooked up from the screens and features :D, about -10/15% vs Gen3.
    I wonder if there is room for improvement considering:
    1) break in period
    2) dynamic front grill
    3) better cabin insulation not just from noise, but also from cold/hot air from outside (the Gen4 felt warmer than the fridge the Gen3 feels like when entering it after staying out) --> less A/C-heating necessary
    4) more efficient drivetrain --> shorter warm up times (the Gen3 ones are already quite good, BTW)
    5) more efficient electric motor, power electronics and battery, and higher EV only speed --> better chances to glide or to accelerate in EV mode only compared to Gen3

    I have extensive data about fuel consumption of my Gen3, will be glad to post my results once I get my hand on my Gen4 sometime in the next few months (delivery expected mid-July.... :( )
     
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  10. TheChosenOne

    TheChosenOne Member

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    Everyone has been saying this, cold weather effects MPG numbers negatively and I found out it truly does. Here in the Bay Area for the past week, it's been raining and even though it's in the 50s to low 60s Fahrenheit when raining, the wind probably makes things colder. I did my absolute best to get the highest MPG I could get and I only got around mid to low 50s. In warmer weather I've easily gotten mid to upper 60s MPG.
     
  11. krousdb

    krousdb NX-74205

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    800 mile per tank challenge | Page 2 | PriusChat
     
  12. JohnF

    JohnF Active Member

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    I agree with you completely that mpg data is a tricky business. As just one example, take temperature. I bought the Insight-I to commute back and forth to work, 34 miles each way. Once I had learned how to drive it and figured out the route, it gave summertime tanks at 103+ mpg, whereas I struggled to maintain 80mpg over the winter! Same car, same driver, same route. And that's just ONE variable.

    I don't post to any of the online databases, mainly because my science training rebels at bad data. Again taking temperature as an example: what number should I post for a tank? Should I record the temperature at both ends of each trip (where I worked was usually 10F warmer than where I lived) and then average those, weighting by the length of each trip? Is it even valid to average temps? What to do about speed, which varies even more during a trip? How to factor in mpg when I have a boat on the roof? A leadfoot driving my car? And so on. So I keep a private spreadsheet with notes indicating special factors.

    Something else to consider is warmups. which can have a huge effect on MPG depending on what the starting temperature is. In winter a car stored in a heated garage can be far warmer in the morning than one parked outside. In summer, mpg is better in part because warmups begin from a higher temp. The Insight-I's mpg was particularly sensitive to low temp warmups, so some owners resorted to electric block heaters to eliminate this annoyance. I probably would have if I had a garage with power.

    But it's important to be aware that much higher mpg can be reached with a fully warmed up car. It's easy to check this by zeroing Trip A when you start the car and Trip B as soon as it has warmed up fully (probably need a ScanGauge set to display coolant temp), taking a drive, and noting how long it takes the average mpg's in Trip A and B to equalize.

    Warmup may account for some of the differences in mpg's published by different testers. From Wayne Gerdes's test linked above, it looks like he takes the car on a calibration run to check the accuracy of its odometer (vs GPS) and MPG display (vs GPS divided by topoff volume). After this the car is fully warmed up and he does his mpg testing. His mpg numbers may seem amazing, and the typical driver may not hit those numbers because they usually add in the effect of the warmup.

    But Wayne is doing it the "right" way, because his method eliminates the variation from warmups starting at different temperatures. Plus his higher numbers generate interest, probably not a bad thing as long as people don't get too upset when they can't reach the same numbers he gets.

    Sorry, hope this is not too far OT, but "real world MPG" is like waving a red flag in front of me. It would be so much better to think of a range or even a distribution plot rather than a single number.
     
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  13. JohnF

    JohnF Active Member

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    Rain can decrease mpg, especially standing water on the pavement which causes drag on the tires. It's also likely that wind decreases mpg unless it is a very smooth breeze from behind. Side winds and gusts can disturb airflow over the body, which is designed for efficiency mainly for airflow from dead ahead. My impression is that I get best mpg on days when there is little wind.
     
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  14. bwilson4web

    bwilson4web i3 and Prime

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    Actually, we're on the same page:
    My first Prius chart:
    [​IMG]
    Notice the data point in the top-right, the "Air trip" MPG. It comes from a habit developed in 1971-75 when I owned a 1966 VW MicroBus. I recorded the tank MPG in a 'blue' composition book and found it was a great way to detect spark plug, valve backlash, or low tires long before it was visible. In effect, per-tank mileage is an early indicator that the car needs maintenance.

    So when I picked up our new, 2010 Prius, I benchmarked the car on the way home to generate this chart:
    [​IMG]
    The only data point I had to do on the weekend was the 80 mph test because I wanted to avoid traffic (aka., the ones with the lights on the top.) So I'm happy to see Wayne has adopted this practice because that was not the case in October 2005 when I first ran into him at GreenHybrid.com.

    Now one area I have been investigating is modeling our Prius thanks to [email protected]:
    [​IMG]
    [email protected] turned me on to the drag force formula found in a Toyota sales brochure. It was easy to develop a spreadsheet model that has 'close enough' accuracy to real world metrics. Notice that a continuous function doesn't handle control law discontinuities. But like all models, they don't have to be perfect (aka., @austingreen.) Differences between a model and reality provides insights pointing to areas to investigate. For example, the 70-75 fall-off in Gen-1 Prius MPG turned out to be 'fuel enrichment' to protect the catalytic converter.

    What I need to do next is use the Gen-3 metrics and EPA roll-down coefficients to make a model. Then resolve the differences with my field studies. Once that is worked out, I'll be able to use the same method with the Gen-4 knowing there are some unknowns. In particular, I will need the vehicle overhead load (i.e., the power draw when the warmed up car is stationary with engine running in "N" and engine off in "N".)

    Later,
    Bob Wilson
     
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  15. mozdzen

    mozdzen Active Member

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    I'd like to see similar charts to these once you get your all EV vehicle. The graphs would simplify slightly, but then you could find other variables, like state of battery charge, extra weight in the car, etc.
     
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  16. krmcg

    krmcg Lowered Blizzard Pearl Beauty

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    3000 miles.jpg 3,000 mile check-in. And yes, 68,4 is the lifetime MFG MPG (Trip "B")
     
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  17. krousdb

    krousdb NX-74205

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    Can you switch to the Ave speed and EV ratio screen for trip B and see how many hours you have? I am concerned that it rolls back to 0 after 99:59.
     
  18. krmcg

    krmcg Lowered Blizzard Pearl Beauty

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    Gen 4 LMPG | PriusChat
    It does seem to "roll over".
     
  19. krousdb

    krousdb NX-74205

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    Yes. So that means that we can't prove that it is a lifetime average by doing the math. But if you never reset Trip B, the miles driven will equal the ODO so that will be proof enough. Since I have already reset trip A and B, that won't work for me.
     
  20. krmcg

    krmcg Lowered Blizzard Pearl Beauty

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    I have always used "B" for oil changes. This time I will try very hard not to reset it. We'll see how long it goes...
    I'm disappointed that the "all-up" odometer uses the "since-reset" MPG.
     
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