Easy question - MPG

Discussion in 'Generation 1 Prius Discussion' started by ronlewis, Sep 12, 2019.

  1. ronlewis

    ronlewis Member

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    So, I took my completed car out for a decent drive, about 20 miles. Lotta traffic so I sat at some lights, a little stop-and-go, and when on the freeway (about half the miles) never got over about 55mph. Didn't go overboard on trying to maximize MPG, but did keep my foot out of it for the most part. I averaged 55.1 mpg.

    I seem to recall when I last drove a good running Gen 1 that the mpg seemed to get better around 70mph, at least by the running average. Does that sound right to y'all? I'm tickled with 55mpg - my truck gets 9-10 and my Camry gets in the low 30s, I think (never tried to get an accurate measurement).
     
  2. AldPixto

    AldPixto Junior Member

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    That's awesome. I get around 44 mpg on my 02. It would probably be a few mpg higher if I had LRR tires instead of my all-season Nokian tires.
     
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  3. ronlewis

    ronlewis Member

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    That's what I used to get the last time I had one of my cars running. From reading here, it seems that as the battery fades, the mpg decreases. This car has the freshly rebuilt battery. But, again, small sample size, but I tried to get a variety of driving conditions. Should have two more of my cars ready shortly, both with older batteries; we'll see how they do. I just wondering what this one would do going 70mph out on the open highway.
     
  4. Sandy Meyers

    Sandy Meyers Member

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    My 02 which I still have even in its prime at best got about 50 MPG. These days on highway trips to the desert I’m averaging about 45-ish.

    Most of the time I’m using it around town for shot hops here and there and I reliably get about 33-35 MPG.

    The spark plugs have never been replaced on it and I’m wondering if this my up my mileage back to the expected 50 MPG. The Gen 1 never was expected to get 70 MPG.

    By the way if anyone is looking to buy an original like-new Gen 1 Manual (2001), I have it. Please contact me. Toyota sent me one while I waited 6 months for my 2002 purchase.

    I check in here from time to time so please be patient I will respond.
     
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  5. Mendel Leisk

    Mendel Leisk Obtuse Angler

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  6. WHCSC

    WHCSC Member

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    OP said 70mph not mpg

    I'm happy with anything from 40-50
     
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  7. ronlewis

    ronlewis Member

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    Thanks, WHCSC, I didn't know where the 70 number was coming from.

    But no one is answering my question - do you see better mileage driving 55mph or 70mph? Common sense says 55, but sometimes the gear ratios in the transmission (old cars in the rear differential) can have a higher "sweet spot." Just recall before my first Gen1 seeing higher numbers on my screen at 70, but it might have just been some coasting/foot off the gas involved.

    During my test yesterday, I'd say that most of the time, I was around 52-53, but when I pulled in the driveway, I was at 55.
     
  8. ronlewis

    ronlewis Member

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    I bought my first Gen 1 in from a lady in Chicago who was moving to NYC and wouldn't need a car. Had less than 20k miles, but it had been totaled in a wreck and had a salvage title. Couldn't tell at all by looking or driving it. I flew up there and drove it back to Dallas, cost me less than $30 in gas. I was amazed. It was my daughter's graduation present and we still had it in the family until a couple of years ago when a nice couple bought it for their daughter's graduation.

    Funny, it had recurring instances of the orange triangle. In hindsight, I'm sure it was the HV battery, but the local dealers knew nothing about it. However, because of the salvage title, it was no longer under warranty. That didn't occur to me...or the dealers since it was so new. Had three different ones service it - not sure what they did, but the triangle would go out for a few months - before realizing that it wasn't warranty work, and then didn't charge me since they told me it wouldn't cost anything, lol. The battery finally died, and rather than pay $5k for a new one, I parked it for several years. Later got a Dorman battery for $1800 installed by Chris Auto in Dallas (great guy and member here), and drove it a few more years before selling it with about 180k miles.

    Funniest story was the first time I took it to be inspected, and they guy didn't know what to do with it since the engine cut off and he couldn't get a required exhaust test. He'd never heard of such a thing, but finally concluded that it probably passed.
     
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  9. Mendel Leisk

    Mendel Leisk Obtuse Angler

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    There's a pretty much steady relation between speed increase and mpg decrease. Gen 2 graph here, but I don't think gen 1 would vary:

    Updated MPG vs MPH chart | PriusChat
     
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  10. ronlewis

    ronlewis Member

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    Thanks, Mendel. Makes complete sense. I wonder how accurate the mpg gauge on these cars are. I know they're pretty useless on a lot of cars, more like the tall bar graph on ours that provides the "instant" mpg. I've never done a true test by filling up and dividing miles by gallons. Probably because...why care, lol? At this mileage rate, it's all good.
     
  11. Mendel Leisk

    Mendel Leisk Obtuse Angler

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    I find our 3rd gen mpg display (liters per 100 km, but same thing) is fairly consistent, but also fairly consistently biased: it will reliably over-report mpg by around 7.5%, comparing to calculated. The most likely reason for that is very likely Toyota's marketing department?? It's kinda sad, considering they're pretty much the mpg leaders, so why cheat the numbers?
     
  12. ronlewis

    ronlewis Member

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    IMHO, anything over 50mpg makes me notice. Under that, not so much, although still good. Mktg probably trying to get to that "take notice" level.

    Just got back from another 15 miles, hardly any of it freeway and the whole time with the AC on (rainy cool yesterday), so it kept running at traffic signals. Now, my cumulative mileage is down to 45.
     
  13. Mendel Leisk

    Mendel Leisk Obtuse Angler

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    Our 3rd gen, 45 kms into the tank (with reset trip meter) was at 3.6 liters per 100 km (65 mpg US):

    IMG_1148.JPG

    Then my wife went off for a serendipity shopping trip, and when she got back it was at 4.3 liters/100km (55 mpg). Then a couple of days of ferrying the grandkids up to a school atop the highest jeesus hill in Port Moody, and a Costco run (nice and flat terrain), we're now up around 4.6 liters/100km (51 mpg). I think it's more-or-less stable there, might be able to coerce it back to 4.5, who knows. Still that's displayed, which'll likely translate to around 4.9 liter/100km calculated (48 mpg).

    We're rolling on the porker 17" Toyota rims and newish Michelin Primacy MXM4, which is imposing a bit of penalty.
     
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  14. jb in NE

    jb in NE Senior Member

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    This should not be the case. At higher speeds, there is higher aerodynamic drag and more power is required to propel the car, thus more fuel to provide the power. If you were to drive the same course at 55 mph and at 70 mph, you will consume less fuel at the lower speed.
     
  15. ronlewis

    ronlewis Member

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    Yes, I'm sure that's true, but again, with the exception that gear ratios can make a difference. I have both an F450 truck and an F350. Same engine, trans, body, and interiors, and yes, the 450 has heavier axles and suspension, but still, at the same RPMs, it also goes considerably slower and, of course, gets less mpg. It also seems, although I've never measured it, to get better mileage once Overdrive kicks in than it does if I leave it in Tow Mode, which doesn't use Overdrive.
     
  16. jb in NE

    jb in NE Senior Member

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    The Prius has a CVT and keeps the engine in what it calculates is the optimum RPM range. Typically in the 2000-2500 RPM range.
     
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  17. ronlewis

    ronlewis Member

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    Cool, that's the answer to my question. My experience of seeing, IIRC, my mpg number go up after accelerating up to 70 from 55 was simply a product of, I expect, me leveling off the pedal once I reached that speed. I.e. we get better mpg while cruising than while accelerating. Just as I'd get worse mileage when slowing down to 55 while going up a hill.
     
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  18. nerfer

    nerfer A young senior member

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    55. For sure. There were charts made a long time ago on this, I don't have them at my fingertips though. Even though the Prius has a CVT (technically, a planetary-gear system, at least on models since 2004, not sure about Gen 1), at higher speeds it still needs to rev higher and will consume more fuel. Not to mention wind resistance increases by velocity squared.

    With the Gen 2 Prius, I have heard the adage 60-60-60 : going a steady 60 mph (on a flat route) at 60'F (no heat or A/C needed) will result in 60 mpg. That might be a little optimistic.

    Technically, the best mileage possible is using pulse-and-glide, maxing at 40 mph.

    Edit: here's one chart: Updated MPG vs MPH chart | PriusChat
     
    #18 nerfer, Sep 12, 2019
    Last edited: Sep 12, 2019
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  19. ronlewis

    ronlewis Member

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    Yeah, I've seen the pulse-and-glide effect. Works on the GF too!
     
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  20. Alex MM

    Alex MM Junior Member

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    John1701a's Toyota Prius User-Guide for the Classic Model (2001-2003) states:
    "62.1 MPH (100 km/h) is the optimal (most fuel efficient) fast speed. So you'll notice a MPG drop driving at 70 MPH (113 km/h), though it isn't huge. But faster than 75 MPH (121 km/h), it is. If you drive fast, you'll consume quite a bit more gas."

    I cannot find the article on my laptop, but I recall 100 km/h also being cited as optimal in an IEEE Spectrum article.
     
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