Maxed out my own efforts, what is next?

Discussion in 'Gen 3 Prius Fuel Economy' started by Brett., Jun 27, 2012.

  1. Brett.

    Brett. Junior Member

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    I bought my 2011 Prius. I watched the Maimizing your MPG video. I read hundreds of threads on this forum on technique, and I'm at a standstill in terms of my MPG. If I annoy other drivers, I can manage about 54-56 mpg by manual calculation. If I go with the flow of traffic, I get between 47-48.

    I never thought I'd say this, but when I don't see my estimated mpg reading a steady 56 or higher (54mpg in reality) I'm troubled.

    "What, how dare my car only get me 4 mpg better than advertised, effectively doubling what my previous new vehicle was getting." Haha

    Given the fact that my house, and place of work are at the bottom of large hills, and the short drive of 7 miles in between is all hills, driving techniques have little if any room for improvement.

    I then decided to research every idea I could come up for increasing battery potential.

    - Can't charge the HV battery while the car is off because the terminals are not active when the vehicle power button is switched off.
    - Even if I could bypass this, I haven't yet figured out how to build a charger that will only charge the HV battery to "80%" capacity as to not over charge it.
    - Adding an additional dissimilar battery pack comes with it's own inherent issues such as the fact that the factory regeneration system won't charge the added battery, cells have to be monitored individually, the packs will not charge or discharge at the same rate, and I'll need a battery management system.
    - The cost of any of the commercially available PHEV kits is ridiculous.
    - Outside of the "cool factor" there is no way to justify spending 10k on any additions to this vehicle as they will not pay for themselves.

    With that being said, am I maxed out for MPG?

    The only thing I hadn't yet considered are LRR tires. My car is brand new, I can't justify switching yet.

    (Listens to crickets chirp.)
     
  2. F8L

    F8L Protecting Habitat & AG Lands

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    Make sure you watch this one too. Works for low speed driving and minor hills.​
    When you get around to it get a set of Energy Saver A/S tires. Most of us see a 2mpg-3mpg improvement over OE tires.Remember that low speed driving is all about reducing rolling resistance so tires and inflation pressure is very important. Make sure you are gliding as much as possible and in open loop. I found that if I don't lift off the throttle completely before starting a glide I may not get into open loop quickly or even at all.​
    You could also look into a engine block heater and grille blocking for colder months.​
     
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  3. Insight-I Owner

    Insight-I Owner 2006 Insight-I MT + 2011 Prius

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    The tires that came on your car are LRR. Inflating them to the pressure marked on the sidewall (probably 44psi) cold (e.g., before driving in the morning) will probably help. Use an accurate pressure gauge to do this: a dial or a digital one, they aren't that expensive.

    Not sure what you mean by annoying other drivers. If driving the speed limit annoys them, that's too bad - or if it's a multilane roadway they can move to the left and go around you. There's a narrow winding 2-lane road near my place that runs along the river. Lots of blind turns, bicyclists, driveways, runners/pedestrians, etc. Speed limit is 25mph. Folks like to whiz along at 40-ish on it (often juggling their handheld cell phones) and come sailing up behind me. Sorry, I'm not going to risk flattening a bicyclist just to keep a speeder happy.

    Try focusing on identifying periods when there is no traffic behind you and then slowing below the speed limit if that will help. Ease up to the limit if traffic appears behind you.

    Can you offset your schedule a tad if that will improve the traffic situation?

    7 miles is tough, flat or hilly, because the car is warming up during a large portion of the trip. A block heater might help. If you can combine errands with your commute that will be overall more efficient.

    Others here may have additional ideas.

    P.S. Get a Scangauge 2. That will give you a better idea what is going on with the car.
     
  4. F8L

    F8L Protecting Habitat & AG Lands

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    Insight-I Owner just made me think of an idea. :)

    Try picking apart your total commute. Print out a map of it from Google Maps. then for each hill or other challenging section try to identify the reason you are having a hard time with maxing mpg. Is it elevation change? Traffic? etc.. Then when you approach that section of road reset your trip meter and make adjustments to your driving technique and mentally record the mpg and the technique, speed etc. for that section. When you get to work or home add those details to the map. Do this for each section or road and then combine the adaptations to your total commute and see if it helps your overall numbers.
     
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  5. Insight-I Owner

    Insight-I Owner 2006 Insight-I MT + 2011 Prius

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    This is absolutely a great idea. Not only does it help you on your commute, but it also teaches you how to deal with similar situations you encounter on other trips.

    I did something similar on my commute and it helped tremendously.

    An extra benefit was that it changed my commute from a dull boring chore into an interesting game that I actually looked forward to.
     
  6. qbee42

    qbee42 My other car is a boat

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    Your mileage isn't bad for the type of commute you drive. If you want much better, you need a PHEV or EV.

    Tom
     
  7. Insight-I Owner

    Insight-I Owner 2006 Insight-I MT + 2011 Prius

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    Or a bicycle.
     
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  8. bielinsk

    bielinsk Gremlin

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    This type of driving is the reason people discriminate against Prius drivers.

    Try this in LA and see what happens.

    I would rather get 50 MPGs and not worry about someone following me or shooting at me.

    Courtesy goes a long way.
     
  9. F8L

    F8L Protecting Habitat & AG Lands

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    Then we would miss out on your super helpful posts like the one above! :)
     
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  10. tedjohnson

    tedjohnson Member

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    I would do all the above and make sure I drove uphill in ECO mode and only used enough gas to keep the eco light on, unless it held up traffic. The prius works well starting out at the bottom of a hill and climbing it first then descending - I can usually get 64 mpg doing that, even with a cold start. But you start up at the top and waste the gas going down while the engine warms up before it allows no gas coasting. Thats tough. The PIP will let you do that and it seems like the hatchback should also, but it does not. All because it is programmed to let you have a warmed up ICE and CAT when you need it. Even trying to coast engine off in neutral will bring on the ICE as you start downhill. The only way around this, is going to be some kind of defeat switch that locks the ICE out and allows a coast. Maybe someone here has figured out how to do that - Bob Wilson or Ken in Japan. I am sure it would void the warranty as well.....
     
  11. qbee42

    qbee42 My other car is a boat

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    Is this something new with the Gen III? With the Gen II HSD, the ICE cannot start in N no matter what the conditions. If it is running when you shift to N it keeps running. If it isn't running, it can't start.

    This is the reason people warn against coasting down large hills in N. If you shift into N with the ICE off, you can theoretically over-speed MG1 as the motion of the wheels forces it to spin too fast. In normal operation the ICE starts to turn to limit MG1's speed, but it can't do this in N.

    Tom
     
  12. Brett.

    Brett. Junior Member

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    I guess I forgot some details. Thank you all for the posts, definitely some food for thought.

    I have my tires inflated to 45psi, and the cars been in eco mode the entire time I've had it, except when I tried power mode and realized if I left it there I'd get 40 mpg easily, I used to have a heavy foot.

    Luckily my hours right now are 1130am to 930 pm so there's nobody on the road at those times in this rural area.

    Getting to work and coming home, as mentioned are steep hills. Leaving my house it kills me, and leaving work it kills me. Both big hills on a cold engine. Is it better to just give it hell and get up them asap, or just do what I do and chug along below the limit (with nobody behind me) but the battery doesn't charge and then coast down the next hill.

    The rest of the hills are relatively small and you can't use the battery to power up them, and while trying to go 45 -50 mph, the ICE keeps turning on so I try to avoid 47 mph like the plague when it turns on. Some how now the engine on that portion of road will now start itself at 45 mph even if I'm coasting.

    The only explanation I can come up with for that is that the engine is cold at that point from limited engine use and is warming itself up again?

    Short trips :/

    Well, anyway I just came across the Enginer start kit, the 2kwh one. I suppose at tax time I could spend $2,000 and buy that kit, but is it a waste, or does anybody think that on hilly terrain it might actually get me the 14.5 miles round trip to work and back? If it could do that, I could probably justify the cost.

    I will see about getting Energy Saver tires as soon as mine run low, but I've only got 4444 miles on the car as of yesterday so the tires are hardly broken in.
     
  13. tach18k

    tach18k Member

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    In PWR mode I can get 45mpg or better with my hills and valleys on my drive. 50 feet of full power mode going uphill, will take about 12 miles of 99% electric to recover back to 50mpg on CONs. I'd rather have that power up a hill at 60-70mpg than putt along at 42 to make up the mpg, in the long run, its the price I pay at the pump that I look at. getting 45-47mph I'm fine with.
     
  14. Brett.

    Brett. Junior Member

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    Well, I watched that video today with the neutral coasting and gave it a try. I've actually never had my MPG gauge up this high before, my first tank was filled reading 58.8 and normally when I get around 58 I couldn't get it any higher since.

    Who knew? The "Glide" in the Gen 3 still has resistance even if you let off the pedal, and depress it to such an extent as to have nothing register on the HSI display, there is still drag. Putting the car into neutral the first time I could clearly feel the difference in coasting vs the simulated "Glide." My speed down a certain hill today was 11 mph faster in Neutral than it has ever been while having nothing on the HSI in D.

    Something note worthy, since neutral doesn't allow regen braking, when going down exceptionally long hills, I find it beneficial to maintain speed limits and regen brake periodically and leave it in drive. For short / small hills or straights going under 50 mph, neutral maintains speed much further than "gliding."

    Clearly the use of neutral to maintain slower than highway speeds is where a lot of MPG are going. I found that on a road I used to navigate exclusively with battery power until the ICE had to run 4 times in a 14 mile stretch, the ICE only turned on twice today from N + Battery. Maximizing regen braking recharge every chance possible helped delay the need for the ICE.

    Makes me wonder what else I'm missing.. Glad I started this thread, perhaps somebody else will find this useful. Thanks again!

    300+ miles on half a tank of gas makes me feel good. My previous vehicle needed gas around 240-260 miles.

    [​IMG]
     
  15. F8L

    F8L Protecting Habitat & AG Lands

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    Nice work, Brett!

    The only concern I have with neutral is whether or not it kills fuel consumption completely like warp stealth or glides do. In the GenII I could warp stealth down a long hill at infinite mpg but if I shifted to neutral I could only get 350mpg. I suspect this is a result of the ICE being on when i shifted to neutral. I will check to see if this is the case with the GenIII on my next commute. I'll verify using the scan gauge and looking at open vs. closed loop.
     
  16. Brett.

    Brett. Junior Member

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    Well, each time I shifted into neutral the engine stayed off (after lifting foot off accelerator) except one instance after a long stretch of battery and neutral I'm pretty sure the engine started in neutral down a long hill probably due to coolant temp dropping too far? I was sort of distracted talking to my gf when it occured, but I'd like to know what you find also :)
     
  17. F8L

    F8L Protecting Habitat & AG Lands

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    Make sure you don't start off in neutral below 42mph? Then accelerate higher than 42mph?. It is ok if you shift into neutral at speeds over 42mph and coast down.
     
  18. Brett.

    Brett. Junior Member

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    Uh oh, will that do damage to MG2?
     
  19. F8L

    F8L Protecting Habitat & AG Lands

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    Supposedly. I've never heard of a failure but that is what Tom and Seilerts say and I believe them. LOL
     
  20. Brett.

    Brett. Junior Member

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    I found this on an older thread about neutral coasting. (edit) seems to have most complete info I've been able to dig up yet.
     
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