After 4 years, I am finally getting good mileage ...

Discussion in 'Gen 3 Prius Fuel Economy' started by PriusRos, Jul 3, 2013.

  1. PriusRos

    PriusRos A Fairly Senior Member - 2016 Prius Owner

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    **Warning - Long Post**

    I had a Gen II 2006 Prius and over its 3-year lifetime, it was only averaging 43 mpg. It started out higher because I was driving longer distances. It did have a couple of 50+ mpg tanks, but that was only when I was on a road trip. When I bought my Gen III in 2009, I had heard all the hype and was hoping to see much better results, so was disappointed when I didn't do any better.

    I tracked my mileage for the first 30 months and my lifetime average came to just over 43 - the same as the previous Prius. Most of my tanks were in the mid-40s, with only a couple reaching 50 or more, and several as low as mid-30s. My low overall mileage was because during the week I was driving just a few miles a day to get to the Metro station and back and the engine barely had a chance to ever warm up. Also, where I live, there are a lot of stop signs, traffic lights, hills, and traffic.

    Two months ago I changed my job location and am now driving 52-54 miles each way to work. It's a very hilly ride, with 90% highway at 55 or 65 mph. My usual speed is between 61-67 mph. Since starting the new job, I started tracking my mileage again. At first I was getting around 47 mpg at fill-up but now I am consistently getting 50+ mpg tanks (calculated). Now that I have a consistent 100+ mile daily commute I can track the factors that seem to make a difference.

    1) Energy Saver Tires: When I was first getting the 47 mpg tanks, I was driving on the OEM Yoko tires. I bought some Michelin Primacy tires and my mileage immediately dropped to around 43 mpg on the first fill-up! On the second fill-up it went up to around 45 mpg, but after 1000 miles I decided to exchange them for the Michelin Energy Saver All Seasons. My mileage immediately went back up to 48 on the first tank.

    2) Weather: Mileage dropped a bit on second tank because of rainy conditions. However, I have since driven in the rain and have maintained high mileage.

    3) Using Cruise Control: Again, my route is extremely hilly. I am going up and down hill all the way. I have tried the DWL technique and it just doesn't work for me. Although traffic isn't heavy, there are always cars behind me and everybody drives above the speed limit. And even if there aren't any cars, some uphill climbs are really long and I would find myself slowing down way too much and having to gun it to get back up to a decent speed. I have found that using cruise control to maintain as constant speed as possible gives me the best results. Even when I set the CC fairly high - 66-69 mph - I do much better than when I'm constantly speeding up and slowing down to compensate for hills and traffic.

    4) Distance, stop-and-go, and hills: Normally, my mpg readout does not reach the mid-40s until I've gone about 10 miles. Then it reaches the 50s at around 15-20 miles. There are several factors - from my house to the highway, there are 6-9 traffic signals (depending on which route I take) and most of them turn red. (I think my Prius has a red-light triggering device built into it :) ) It is also very hilly. So between the stop lights, traffic, and hills, the first few miles are mileage killers for my poor little Prius. My mpg readout reaches its highest point about 30 miles into my trip. On the way TO work it sometimes gets as high as 60 mpg. However, a few miles before I reach work the speed limit slows to 45, there's a light at the bottom of a hill, and the speed limit goes up to 60. Over the last few miles my mpg readout drops about 3 mpg. I make up 1 mpg on the final 1/2-mile leg.

    5) No-ethanol gas: Okay, I've only filled up for the second time today on zero-ethanol gas so I can't say for sure. I only put in 6 gallons on the last fill-up, so my tank was not completely ethanol-free, but my calculated mileage on today's fill-up was 51.3 mpg, which is one of the highest tanks I've had. The next time I fill up, I would have been using a 100% ethanol-free tank. I found this gas at a Liberty station in Charles Town, WV, which is a few miles from where I work. There is no ethanol-free gas anywhere near where I live (Washington DC metro area).

    6) Normal, ECO, or PWR mode: I don't think it makes any difference at all. I usually have it on PWR mode while I'm on secondary roads because it's much easier to get up the hills from stops. Sometimes it's on the whole time and I see no drop in mileage. I can't stand ECO mode if I need to get up to speed or pass - it feels so sluggish.

    My point for writing all this: if anybody is disappointed with the mileage they are getting, it is very likely due to the driving conditions rather than poor technique or something being wrong with the car. The biggest mileage killers are:
    • Short trips
    • Stop-and-go (red lights, heavy traffic, etc.)
    • Hills and curves
    • Bad weather
    • Excessive acceleration and braking
     
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  2. bisco

    bisco cookie crumbler

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    yaaaaaaaaaaaaaaaayyyyyyyyyyyyyyyyyy!!!!!!!!!!!!!!!!!!!!!!!!!:p
     
  3. prius_in_pa

    prius_in_pa Junior Member

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    Thanks for the post. I just wanted to point out that too many people are over concerned about short trips. Short trips aren't as bad as one may think. I agree that short trips are MPG killer but what does it really mean? Let's say I lived 5 miles from work and make that short trip and get poor MPG, at the end of the day, I'd still be much greener than someone who lived 50 miles from work even though he would get much better MPG making that long trip. My 5 miles trip would only consume a little over 0.1 gallon of gas. The 50 miles trip would consume closed to 1 gallon of gas. Better MPG doesn't always equal greener.
     
  4. PriusRos

    PriusRos A Fairly Senior Member - 2016 Prius Owner

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    You are right, of course, but my reason for this post is for those people, including me, who bemoan the fact that their stats never seem to live up to the 50-60 mpg per tank that others in this forum are reporting.

    And I also never understood the EPA estimates that give equal or better mileage for city driving than for highway. At least in my case, city driving means many short trips and stop and go due to lights, traffic, and turns. What do they consider "city"?
     
  5. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    To address higher city than highway, that is how hybrids work. However city trips need to be long enough or at least hot enough. For instance driving around town I get 60's. Driving on the highway at 80mph speeds, mid 40's to low 50's.

    In the city, you have lots of opportunities where you are moving but the engine is off. Everytime you come down to a stop light or traffic, you are getting infinite miles per gallon which raise your average. Also it is rare that you are driving 80mph or even 60mph in town, so you are not fighting the air as much.

    In non-hybrids, the city is lower because there are lots of times when you are stopped and the engine is running putting 0mpg into your average. So lots of starts and stops with an engine that can't regulate its output efficiency in any way, means it will be lower.
     
  6. prius_in_pa

    prius_in_pa Junior Member

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    Good point. Also when driving at low speed, you'll be gliding with ICE off and not turning. At high speed, even if you get a chance to glide, the ICE will be turning with no fuel feeding to it. The turning of the ICE will increase drag.

    When driving on local road below 40 mph, I could easily get 60 to 65 mpg
     
  7. PriusRos

    PriusRos A Fairly Senior Member - 2016 Prius Owner

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    when you say you get 60-65, are you talking about the mpg instantaneous readout or the calculated average for the tank? Yes, I can get 100 mpg in some cases, but when my driving consists of only short, start-and-stop trips, my calculated average on fill-up is in the low 4os at best.
     
  8. prius_in_pa

    prius_in_pa Junior Member

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    I'm talking about 60 - 65 mpg average of the entire trip. Typically, the distance is about 10 miles.
     
  9. PriusRos

    PriusRos A Fairly Senior Member - 2016 Prius Owner

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    It does seem that other people's experience with city driving is different from mine. But in my case, too, I am not talking about 10-mile trips at a time, but maybe 1-5 miles. It could also be because of the hills around here. If I'm stopped at a light at the bottom of a hill, then I have to use energy to start up again. All I'm saying is that after 7 years of driving two different Prii, I have not been able to exceed the mid 40s average mpg while I'm doing short commutes around town. When I look at other people's stats on Fuelly, mid 40s isn't that unusual.
     
  10. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    1-5 miles contains a 1-2mile problem area. 1-2 mile trips will yank your average closer to 30's. Larger distances will probably start swinging it up to 50's.

    It sounds like you are just running errands, and a PiP would be a better fit. I just got 80+mpg on my last 15mile city drive from house to house. Tank average over ~350miles is sitting at 58mpg.
     
  11. prius_in_pa

    prius_in_pa Junior Member

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    Keep this in mind. ICE is NOT very efficient when you run it at low RPM. To see what your RPM is, you probably will have to get a Scan Gauge. On local roads, I tried my best not to let the ICE come on. But once it does come on, I step on the gas a little harder to get the ICE to run at higher RPM. Besides the warm up period, I always try to either run the ICE at high RPM or let go the gas to turn off the ICE. Once the ICE is off, I either glide or cruise using the battery.


    I make a lot of short trips myself. But I combine them and do them all in one day. During summer time, your car will stay warm for awhile. Your MPG will suffer on the first short trip but your second short trip should show much better MPG.
     
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  12. PriusRos

    PriusRos A Fairly Senior Member - 2016 Prius Owner

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    Since I got my new tires and my new commute, I've been regularly tracking each trip by resetting the B odometer. On my 52-mile trip to work, my mpg readings upon arrival are 52-57 mpg. For my trip home, they are 53-60. If I go out for lunch, a 10-12 mile round trip (with a stop for lunch), my trip averages have been in 39-45 mph. The main road where I work is a 60-mph divided highway - but there are several traffic lights. And it's very hilly. So there is a lot of slowing down and accelerating from a stop or to climb a hill.

    I've also noticed that when I first start out and I'm getting a really low mpg readout, it's much better if I speed up quickly (using the PWR mode).
     
  13. Bingee

    Bingee Member

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    Excellent information thank you.
    I have noticed MPG improvement by changing my tire pressures to 44 front and 42 rear
     
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  14. ImeanGreen

    ImeanGreen Prius v Five BP Brigade #236

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    Got Michelin Defenders @ 38/36 psi averaging 55.5 mpg after 3K miles.
     
  15. PriusRos

    PriusRos A Fairly Senior Member - 2016 Prius Owner

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    What are your average trip distance, topography, and traffic conditions? Is 55.5 mpg your calculated tank average or displayed average?
     
  16. ImeanGreen

    ImeanGreen Prius v Five BP Brigade #236

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    Not much traffic with mixed hwy driving and city driving, 55 mph rural hwy and 70 mph interstate. Using cruise control at 55mph and 65mph in eco mode. 55.5 mpg per display. Maybe 52 or 53 mpg calculated. Terrain wise, it's mixed hills and flat but mostly flat.
    You have not mention your psi. I went 3 psi's over what Toyota recommended. I had the yokos that came with the car and they were really good. Got the defenders because of the treadwear warranty. Try raising your psi to 2 over what Toyota recommended and see what you get. I'll mostly go up higher.
     
  17. Mendel Leisk

    Mendel Leisk Sand Pounder

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    To OP:

    I'm in agreement with every one of your points.

    I've found CC very good on this car, raises instant mpg on ScanGauge, well designed.

    ECO vs Normal, no difference, apart from maddening pedal travel in ECO.

    Short trips, yeah, that's us. We recoup it on the weekends. A block heater helps, with short trips in particular.

    Tires: yeah, beating your head against a wall waiting for so-so tires to "break in", vs going with a decent LRR and watching the mileage jump, right from the get go. Only thing, and it's been mentioned: raise pressures, at least a bit.

    Our's has the 215/45R17 (Michelin Pilot, around 38/36 psi), and with the mainly short trips / low mileage (under 15000 km's yearly), guess we're doing ok. ;)

    To contribute another fuel saving tip:

    Stick to posted speed limits, let that speed fall off in advance of corners, slow downs, as opposed to using brakes. Keep a decent buffer in front. Basically drive gently, wherever possible.
     
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  18. PriusRos

    PriusRos A Fairly Senior Member - 2016 Prius Owner

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    I raised psi to approximately 38/36 shortly after the new tires were installed but haven't checked recently. (Checking tire pressure is one of the chores I'm not too fond of.) Next time, I'll try raising it to around 40.

    Regarding speed limits - in this area, nobody drives at the 55 mph posted limit. One has to be going at least 60 in order to keep up with the flow. Even if I'm driving 63/64, there are people whizzing by or coming up rapidly on my rear. At 65 mph, most people are around that speed. Not many drive too much faster probably because there are a lot of hills and curves and the lanes are narrower in some stretches so it can get pretty hairy going very fast.
     
  19. Mendel Leisk

    Mendel Leisk Sand Pounder

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    With the 15" a lot of people set around 40~44 region. I keep lower with our 17", any higher get's pretty rough.

    It's too bad when you're coerced to speed, not sure what the answer is. There are strategies, stick to right lane, get behind (not drafting) a slower moving truck. Yeah right, the trucks are the worst offenders. Anyway...
     
  20. PriusRos

    PriusRos A Fairly Senior Member - 2016 Prius Owner

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    I generally don't like to drive in the rightmost lane because one constantly has to change speed to allow for traffic merging in from the exits.

    Speaking of trucks... one day there was a large truck riding on my tail for a long time. I wasn't in the leftmost lane and I couldn't get into the lane to the right because of traffic. Finally I did manage to get over to the right, hoping to lose him. Guess what, he got in right behind me. I changed lanes again, and he got behind me again!! I managed to lose him finally but I was getting so annoyed. I don't know why he kept doing that. I hate it when people tailgate me, especially a large truck. But I also don't like getting stuck behind a truck because I want to be able to see the road ahead.
     
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