Hypermiling 2016 Rav4 Hybrid

Discussion in 'Toyota Hybrids and EVs' started by drbtz, Feb 12, 2021.

  1. Tideland Prius

    Tideland Prius Moderator of the North
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    The 2016 RAV4 Hybrid would be based on the 3rd Gen Prius. The RAV4 Hybrid got the 4th Gen Prius’ updates for 2019.
     
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  2. mikefocke

    mikefocke Prius v Three 2012, Avalon 2011

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    Rav4 hybrids are made in Japan (3 plants), Canada and Kentucky. I believe the primes are Japan only. I have a '19 non-plug-in. Functional. Powerful. 14k miles, not perfect (no car is) but does exactly what I expected it to do with ease. One T-SB, one CSP. 5th Toyota hybrid in family which shows what we think of them. (Gen3, v, v, Rav4h, Avalon hybrid)
     
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  3. Trollbait

    Trollbait It's a D&D thing

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    While it will lower frontal area a bit for slightly better aero, going smaller tire shifts the final drive ratio to less efficient. Ecomodders will go larger for more efficient drive ratio.

    Wait, are we talking tire diameter or tire width?

    The difference between factory tire options is actually in the diameter of the wheel. The overall diameter of the tire is virtually the same, so the manufacturer can use the same suspension specifications and odometer settings between them. That means going to the smaller factory tire size will require getting a smaller wheel too. That will likely lower weight in the best spot for the most impact, but the efficiency improvement may not be worth the price tag.

    You could try different size tires. Feed your current size to this calculator, and it gives the dimensions in inches and list of other tire sizes that will fit the wheel. Then you compare them to the stock tire dimensions.
    Tire Size Calculator - Tire and Wheel Plus Sizing

    Going narrower tread width could improve aero to a tiny degree. The tire contact patch actually will stay the same, so traction won't change because of that. Changing the tire diameter will change the final drive ratio and frontal area as I went over above. I saw economy improvement with a tire that had a 1% larger diameter. Changing the tire size can mean changes to how the car handles.

    I save such experimentation for when it is time for new tires. You could try increasing tire pressure above the door jamb recommended rating. Higher pressure reduces rolling resistance for better fuel economy, but it will reduce the tire's grip as the contact patch shrinks. Be careful when trying out new pressures, and don't go over the tire's max rating.

    I run partial grill blocks year round. Modern cars come with over sized radiators in case a buyer regularly drives through Death Valley. A full block probably isn't a problem, though I'd check to see if your app can display coolant temperatures. The A/C condenser is also there, and the car does run it during winter to dry the defogger air. If the windows seem extra foggy with the full block, that is why.

    It might be possible to direct air through the defogger vent without turning on the defogger. It is on the Prius Prime. If that works for clearing the windshield, you'll save energy by not running the A/C unit.
     
  4. drbtz

    drbtz New Member

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    Yes, thank you! I was trying to do specific reading on how HSD works and how I should coax the pedal for "golf cart" mode, etc. but kept getting stuck finding out which gen the Rav4 fell into.

    Trollbait, that all being the case I don't see a valid reason to switch tire size then. The recommended width and side wall seem good to me and I'm assuming to go down in R value I'd need new rims.

    Also good call out in the A/C thing. I noticed in a couple threads people just turn the fan off and set the vents to feet and defrost and with enough speed the latent heat from the engine makes its way in the cab.

    I've been using auto at 70F and once it warms up I rarely see the fan go back over 2 bars so I've kind of left it.

    Side note, thank every single one of you who have commented and helped me learn more about my vehicle. I've honestly learned more off my ONE post here than any other forum I've visited.
     
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  5. alanclarkeau

    alanclarkeau Senior Member

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    You'd have to consider the legalities of putting smaller/narrower rubber on. Whether that would breach TOYOTA's compliance, I'm not sure. You could lose the advantages of a good driving car.
     
  6. drbtz

    drbtz New Member

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    To me it just seems like a hassle not worth it. The engineers know far more about the vehicle than I ever could so I'm sure there's a valid reason esthetically and mechanically for the size tire they chose.
     
  7. Tideland Prius

    Tideland Prius Moderator of the North
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    The ideal way to drive a Toyota hybrid for fuel economy is to use the “pulse and glide” technique. This attempts to take advantage of the efficiencies in either powertrain and reduce the inefficiencies.

    The pulse part means accelerating more briskly than you would think for fuel efficiency. The theory behind that is that you’re using the gas engine in its more efficient rpm range than if you were to accelerate lightly and lug the engine. (You can Google brake-specific fuel consumption or BSFC. It basically a chart highlighting engine power vs. fuel consumption for an engine and can give you an idea of why it can be advantageous to accelerate a bit harder to get the engine rpm into that sweet spot).

    The glide part is then letting the car move down the road without any input from the engine OR the battery or without regenerative braking (if there’s lift-off regen, we call it coasting). With Toyota hybrids, you have to lightly press on the accelerator to get into glide mode. The reason is that Toyota programmed a bit of regen when you lift off off the accelerator pedal to simulate an automatic transmission drag.

    So depending on road gradient, traffic around you and speed limit, you could do something like a pulse to 40mph then glide to 30mph and then repeat. Of course this works well with light traffic so that people behind you can go around you. Or heavy traffic where you can disguise the pulse and glide as you go from traffic light to traffic light (e.g. downtown or similar).
     
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  8. Mendel Leisk

    Mendel Leisk Senior Member

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    I wonder if you could reduce that “delta”, say instead of 10 mph variation, just 2 or 3, and still be effective, in improving mpg? And rather than just letting speed rise and drop regularly, try to take advantage of (aforementioned) circumstances: traffic bog downs, uphill gradients, cautionary slowing down at cross streets or intersections.

    In short: stealth pulse-and-glide.
     
  9. wjtracy

    wjtracy Senior Member

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    The Gen2 Prius was always bad MPG for the first 5 minutes, so it was bad for MPG to turn the engine off at short stops, if you did not have to.

    It seems that problem does not happen so much anymore, such that the 40 MPG we get on 2020 RAV4H is almost if not as good as the Gen2 Prius for local style driving. Not sure about the 2016 RAV4H.
     
  10. Trollbait

    Trollbait It's a D&D thing

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    This also works with traditional ICE cars, though called pulse and coast. There is a Popular Mechanics article from the '50s on the internet somewhere that describes it. Today's hypermilers just rediscovered it.:)

    In my experience, that does work.

    Toyota has been improving on the warm up times. The 2016 Rav4 is probably like the gen3 Prius in behavior.
     
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  11. Mendel Leisk

    Mendel Leisk Senior Member

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    Regarding warm up, if you don’t have a lot of spur-of-the-moment cold-starts, and don’t mind a little fore-planning, installing and using the block heater can help. A couple of hours warm up works well.
     
  12. drbtz

    drbtz New Member

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    Boy I had some responses to catch up on!

    The great thing about my job is I delivery food 5 days a week, 8 hours, and get to try these tips almost immediately.

    I usually allow the engine to run for ~30 seconds in the morning while I brush the snow from windows and make sure my seat is how I like it (changes from day to day depending on how many layers I have to wear for this ridiculous -10F weather). By the time I start delivering I'm at 55C and within one delivery I'm already at 70C and the car faithfully stays between 70-82C. If I leave her "off" because there hasn't been a delivery in 20-30 mins she'll cool down to 50C but get right back up into "operating temp" no problem.

    Would like to hear more from Trollbait on this one. I do have a stretch of about a half mile of back to back traffic lights until I get to the main roads. They eat my mpg so I try to stay in "golf cart" mode for a few blocks until I hit a less congested route. Not too bad in my town, pop of only 75K people.

    So far today after warm up and really planning out my routes to avoid full stops I was able to maintain a steady 33MPG. It's actually closer to 31MPG. I have manually calculated over the last 10 fill ups and found the on board MPG meter to be off by -2.
     
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  13. Trollbait

    Trollbait It's a D&D thing

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    Been many moons since I had a hybrid, and most of my driving these days is only a couple of miles in town.

    Traffic and speed limits made the large speed spread for coast and gliding on the commute, so I went with what I could get away with, which may have been a 5mph delta. When I last had the 2005 Prius, I was averaging 58 to 60 mpg in spring weather. The terrain is not flat here, and I tried to take advantage of declines to extend glides. Still do that with any car.

    Another hypermiling technique is driving with load, which means keeping the load on the engine constant/accelerator pedal in one spot. That means letting the car slow down on inclines and speed up on declines
     
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  14. Tideland Prius

    Tideland Prius Moderator of the North
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    If you can get the engine to its BSFC sweet spot for that, you could. My worry is that the 2-3mph difference would be done in EV mode when accelerating which defeats the purpose.

    Trollbait's seems to think 2-3mph still helps mpg.
     
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  15. Trollbait

    Trollbait It's a D&D thing

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    Yeah, you still have get the engine running where pumping losses are low. Now, at low speeds, I have done EV pulse and 'neutral' glides, but with hills extending those glides.
     
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  16. Mendel Leisk

    Mendel Leisk Senior Member

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  17. drbtz

    drbtz New Member

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    Alright let's talk for a minute, how am I supposed to be using battery?

    Let me throw a scenario that happened today at work. I came off a road with a 35 mph limit and coasted down a long hill into a 25 mph zone and just lightly pressed the accelerator to keep 25 mph and occasionally 30 mph. By the end of the half mile stretch my battery was down to 2 bars.

    My mpg was great at 42mpg but I would guess my next trip would be low as the engine would be on longer to replace the SOC.

    So what should I have done here?
     
  18. alanclarkeau

    alanclarkeau Senior Member

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    Yep, I remember that article. I think it was re-published during the '70s Oil Crisis - or copied somewhere (I wouldn't have bought it in the '50s). I've always tried to drive that way, no matter what car I've had - certainly makes a difference. Noticeable when 2 people drive the same car.
     
  19. Tideland Prius

    Tideland Prius Moderator of the North
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    P&G between 25-30mph (or 23-30mph)
     
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  20. Trollbait

    Trollbait It's a D&D thing

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    Try to feather the accelerator so you aren't using EV nor having regen charge the battery. If the speed drops below 25, do a pulse to get to 30mph. That means pushing the car enough to get the engine on, and it feels like faster acceleration than would work for fuel economy.

    If no one was behind you, I'd let the speed drop closer to 20mph. If feathering the pedal isn't working out for getting a no energy flow, and I've it is more difficult on newer generations of the hybrid system, you can also put the gear in Neutral. Don't need to push the button on the shifter to go from D to N, but if the engine is running, it may stay running when this is done.

    The community at CleanMPG.com is pretty dedicated to getting the best fuel economy out of anything. Their founder coined the hypermiling term.
     
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