Huge MPG difference

Discussion in 'Gen 2 Prius Main Forum' started by 05_silver, May 8, 2022.

  1. 05_silver

    05_silver New Member

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    My Prius has 220k miles on it. I bought it from a close friend who had it serviced at the dealer religiously.

    He had owned it new and complained that he could never get more than 40mpg with it.

    On my 8 mile trip, I can only get 35 mpg if I am super careful. I understand that "short tripping" takes a huge hit on fuel economy. The 8 mile trip has about 4 total stops. I read of another poster who advises that they get 45 mpg for an 8 mile similar trip from a stone cold start.

    If I take it on the highway and drive 70mph with it, I average 47 mpg on a 50 mile trip that gradually goes uphill. On the trip back I can get 49 mpg. I have to drive very conscientiously to get these highway numbers.

    If I take it on the highway and experience horrific bumper to bumper traffic, I average 53.5 mpg.

    Any idea what is up here? Mileage numbers were achieved on 0W-20 Mobil 1 AFE. I have since decided to get more aggressive with 0w-16 Liqui Moly being that the car is short tripped anyways.

    The vehicle has a new 12V Battery. Dr. Prius says 61% Battery life remaining.

    Thanks.
     
  2. PriusCamper

    PriusCamper Senior Member

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    Keeping your car well maintained, as well as hybrid battery health can boost mileage. I've found lots of added MPG value with these Lithium packs: https://projectlithium.com/?ref=9qLPw

    But in general mileage between 35 and 53 are considered within range of normal.

    Most effective way to boost MPG is the tires... Low rolling resistance tires will make a huge difference and higher tire pressure will make an even greater difference.

    I recommend to keep adding a a pound or two or air pressure until you notice a slight loss of traction and then back it off a couple pounds. I've found over the years that 47psi in front and 45psi in back is best for MPG in Summer months.

    Of course all the overly obedient and overly nervous nellies on here will wish great harm on you if you go above 35psi because most tires rate max psi at that for liability protection from really bad drivers. However Michelin rate max pressure at 45psi and there's almost zero difference between the tires rated at 35psi compared to Michelin tires rated at 45psi.

    Of course you can count on all kinds of vague threats from ill-informed Prius chat members for saying such things.
     
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  3. fuzzy1

    fuzzy1 Senior Member

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    PriusCamper likes this.
  4. 05_silver

    05_silver New Member

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    @PriusCamper

    Sorry, I failed to mention that the vehicle is already equipped with LRR Ecopia plus tires in stock size. I have them slightly overinflated but not too much since the wife drives the car. Are there better LRR tires than that these days? These are getting fairly close to being considered worn.

    I considered the project lithium pack but I have my reservations. Not particularly impressed with their customer service and articulation when responding to my questions which makes me pause.

    Thanks.
     
  5. 05_silver

    05_silver New Member

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  6. PriusCamper

    PriusCamper Senior Member

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    The Michelins are only slightly better in mpg... But in general there's nothing wrong with your car and MPGs tend to suck around town on cold engine, especially when weather out is below 75' F.

    As for Project Lithium... I just sent you private message so you can ask your questions there. I work with the maker of the pack multiple times a week and have been connecting with him going into a third year now, so can probably address most of your concerns and questions.
     
  7. bisco

    bisco cookie crumbler

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    drive to your furthest stop first, then work your way back. easy on the acceleration, learn pulse and glide.

    your stop and go mg tells me something is vastly different in you8 mile trip.

    70mph, eliminates a lot of the battery.
     
  8. PriusCamper

    PriusCamper Senior Member

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    Also I remember reading an article about package delivery routes and they saved a huge amount of gas by having a computer redesign the delivery routes to maximize the number of right turns, which evidently get much better MPG than left turns. Of course this only applies to countries where you drive on the right side of the road.
     
  9. fuzzy1

    fuzzy1 Senior Member

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    ^ I thought the mostly-right-turn plan was more for saving driver time and reducing collisions.

    Fuel savings on turns comes not from the turn itself, but from the difference in waiting times for interring traffic to clear.
     
    #9 fuzzy1, May 8, 2022
    Last edited: May 8, 2022
  10. Another

    Another Senior Member

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    Driving style is key. Also proper maintenance especially oil changes.
    Use cruise control whenever possible unless in mountains.
    What you will find is that you will adapt to the car and it will adapt to you.
    On twenty mile suburban trips in 40°+ temperatures, I routinely get 60mpg and for some of the five minute histogram intervals it is north of 75 mpg. The battery goes from blue to green and back.
    My car is closing in on 200k miles with original HV battery.
    When I talk to a mechanic at the Toyota dealer I trust, he tells me this is common despite horror stories you may sometimes read here. People come to this forum with problems to post so the sample is often skewed.
    Abuse of the car by skimping on oil changes or infrequent driving can trash the car and the battery.
    The Prius is an amazing piece of technology and the Gen2 is the best.
     
  11. fuzzy1

    fuzzy1 Senior Member

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    Cruise control doesn't work for everyone. While it does seem to help a majority, there seems to be a significant block of drivers who can get better MPG without it.
     
  12. Another

    Another Senior Member

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    If you consider five percent as significant maybe. Depends definitely on terrain but otherwise cruise is nearly alway a winner. Without it the average driver just can’t resist playing footsie with the accelerator. It’s also interesting to watch the battery charge discharge with the cruise on vs the cruises off and trying to keep constant speed with foot.
     
  13. fuzzy1

    fuzzy1 Senior Member

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    I was thinking more like a couple tens of percents.

    But then this is a region where almost no roads are really flat, so even cruise control is "playing footsie".
     
  14. Another

    Another Senior Member

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    yep, mountains are definitely a problems for the Prius
     
  15. fuzzy1

    fuzzy1 Senior Member

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    I guess 'gentle rolling hills' here could be seen as 'mountains' by Florida standards.

    But no, they are not actually a problem for a Prius. It's just that a fairly good fraction of drivers can outperform cruise control's MPG in this terrain. In just about every vehicle, not just a Prius.

    Some commercial truck systems can now use GPS and terrain maps of the road ahead for terrain-adaptive or predictive cruise control that saves fuel compared to traditional dumb cruise control. Both in gentle rolling hills and in mountains. This sample article was written from my home territory:

    Kenworth's Predictive Cruise Control Looks Ahead to Save Fuel - Drivers - Trucking Info

    The better human drivers have been doing this, and more, for ages.
     
    #15 fuzzy1, May 9, 2022
    Last edited: May 9, 2022
  16. PaulDM

    PaulDM Active Member

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    The Scottish Highlands have never been an issue for any of my gen2 or gen4
     
  17. Another

    Another Senior Member

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    key word, Better.
     
  18. Tombukt2

    Tombukt2 Active Member

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    I am a tyre maniac . Used to change like clothes because I could get near free my cousin owns thre store no matter the tyres on my gens2 and 3 tyres have never made more than a maybe 2 mpg diff on a great day . The list of tyres is extensive mich defender 130 plus ea and down to 48 dollar polish things . Seriously the polish tyres lasted 30K less than defenders but cost 48 ea vs the 120 plus . Driving differences of both tires on a prius not worth discussing
     
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