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Old 05-16-2019, 09:08 PM   #1 (permalink)
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P & G RAV4 Hybrid observations from a Newbie

Hello everyone!

New owner of a gently used 2016 RAV4 Hybrid XLE:
https://photos.app.goo.gl/3zM78Thf9gxwaQmJ8

I've been a long time hypermiler in various gasoline cars (nothing special, just high PSI and driving techniques) but this is my first hybrid and also my first SUV.

With that said I've been researching techniques, basically watching YT videos of Prius owners. Here is what I noticed after 3 days of ownership:

- Can run in EV mode up to ~40mph if on a flat surface, but acceleration from a stop or staying in EV mode up a slight incline is borderline "you're gotta get a honked at."

- There is no sweet spot of just coasting like I've seen in Prius videos from throttle play, or at least that I can tell. Either you are charging the battery, using the battery, or using the engine which in turn charges the battery. Only way to free wheel is by shifting to Neutral which I am hesitant. I was also taught not to do that with an automatic or you'll break it, but no idea of a CVT, let alone a CVT in a Toyota Hybrid works.

- Pulse & Glide does not seem to beat out maintaining a constant speed on the highway. I only tried this once on a very hilly commute home, but the combination of unaerodynamic vehicle with some weight just had my speeds falling like a rock once I used the engine to accelerate to desired speed quickly and anything over say 45MPH has the engine kicking in unless you're on a decent decline. I haven't had a chance to P & G at slower speeds.

- My tiny tire inflator just doesn't cut it with these SUV tires. I was able to raise the PSI from ~30-43PSI cold on 2.5 tires before it shut off due to heat. I can't imagine if I were trying to inflate from a flat: https://photos.app.goo.gl/7GPDz92dJpfBPQE18

Good thing I have the big boy ready!
https://photos.app.goo.gl/99QGCuHBrxMpP9zz8

- I miss the rear time tire PSI readings from my now sold 2015 MINI Cooper. I mistakenly thought all vehicles after a certain year were required to give real time readouts, not just low tire pressure warnings. I was wrong! But I was running 45-46 PSI hot and I am considering a scan gauge or reconnecting my ODB2 Bluetooth/Torque app to see if that can monitor. Open to other solutions here.

- Why the RAV4 Hybrid? I plan to retire shortly and live fulltime out of it traveling US/Canada. I wanted a vehicle that was A) better on gas than a van. B) had decent ground clearance for forest roads and BLM land. C) Genuine A/C, not just a roof fan.

Like the subject of my post says, I am a newbie, so if anyone else has figured out optimal driving techniques for this car, please let me know!

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Old 05-16-2019, 09:21 PM   #2 (permalink)
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Nice car!

A couple thoughts:

- I read somewhere that accelerating in EV mode isn't as efficient as using the gas motor, and that accelerating with the instantaneous fuel economy being around half your current speed is most efficient, because having to recharge the electricity used in acceleration is less efficient than using both gas and EV to accelerate. Read this over on the PriusChat forums but haven't driven my mom's Prius enough to determine if this is the case or not. Would assume if true or not, the same would apply to the Rav4 Hybrid since the hybrid systems are similar.

- Tire pressure is the main mod that helps fuel economy on a Toyota hybrid besides watching the efficiency instrumentation.

- Hybrids take longer to warm up so fuel economy will be lower in the winter and on short trips. Partial grille blocks help during the winter even more on hybrids than on regular gasoline cars.

- Pulse & Glide is more for low speed driving where aero doesn't affect things as much. Steady speed is better on highways. P&G helps for speeds < 40 MPH.

- If I remember correctly, the Rav4 has a pretty good drag coefficient (Most Toyotas seem to be pretty good; our '04 Sienna minivan was 0.30) which is great for fuel economy.

- Shifting into neutral with the engine on is fine in any automatic or CVT transmission equipped vehicle. Turning the engine off and doing engine off coasting is bad in an automatic or CVT transmission vehicle, unless the vehicle is programmed to do it automatically (i.e. Prius glide mode). However in a hybrid the best bet (in most cases) is just to coast to stops and down hills with just your foot off the pedal in order to get that little bit of regenerative braking.
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Old 05-16-2019, 09:43 PM   #3 (permalink)
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Ok, thanks for the tips, I'll head to Priuschat for a bit of searching.

Agreed on PSI. I'm fine with hot PSIs up to 48, but when running that high, I really feel the ~need~ for real time monitoring in case I exceed the 51PSI max on the tire sidewall.

I agree MPG is poor during warmup with the engine running, but why would blocking the radiator on the Hybrids or gasoline cars do much? To my understanding coolant is not flowing through the radiator until the engine reaches desired operating temperature on all modern cars.

Thank you for the clarification on CVTs, and I guess it all depends on the state of the battery charge. If it is fully charged (well Toyota hybrids tend to top out at 80% charged in most cases I read), shifting to neutral makes sense, but if still have ability to cram more juice in the battery coast in gear!

Thanks again!
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Old 05-16-2019, 10:05 PM   #4 (permalink)
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If you're worried about exceeding 51 PSI then just fill them up to 45 PSI. 45 PSI shouldn't ever exceed 51 regardless of temperature, and the fuel economy difference between 45 and 48 PSI is pretty much negligible. Of course you can periodically check the pressure manually occasionally, but it shouldn't be an issue.

The grille allows outside air to rush into the engine compartment to cool the engine, which causes the engine to take longer to warm up. Most grilles are overengineered to prevent overheating in very hot climates, so most cars can have part of the grille blocked year round without heating issues, however one would need an actual coolant temp monitor for that. But in the winter, blocking off some of that grille reduces the amount of air coming into the engine bay, which allows the engine to warm up faster. Before blocking off part of the grille in the winter, the Prius would take forever to warm up just because the gasoline motor isn't used as much and so takes longer to warm up. Another plus is that the heater will generally blow in warm air faster since the engine is warming up faster.

No problem, feel free to ask whatever questions you have. There are other members on here who have had experience with the Prius longer than I have who may be able to better answer your questions regarding Toyota Hybrids too.
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Old 05-16-2019, 11:48 PM   #5 (permalink)
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I assume you have LT tires that are rated 51psi--that's cold pressure, not max hot pressure.

Passing air through a radiator creates lots of drag; the less air you let through and send around the car body instead, the lower the drag and better the fuel economy. It isn't just about letting the engine warm up faster, although that is a benefit too.
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Old 05-16-2019, 11:58 PM   #6 (permalink)
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A hybrid has taken most of the improvements in technique off the table and automated them. Little benefit from pulse and glide. Certainly you don't want to use battery power to accelerate. Best to save that for low speed steady cruise.

Best thing you can do to improve fuel economy is drive slower.

I have shifted to N in my Prius to allow the vehicle to keep the engine off while building up speed, but I believe that shuts off an oil pump that lubricates some mechanicals, so I'll leave it in gear from now on. That, and the reason the engine turns on above a certain speed is to keep the MG RPM within safe limits.

I like your idea to travel in the vehicle.
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Old 05-17-2019, 06:41 PM   #7 (permalink)
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Gotcha on blocking the grille to help with aero as well. I'll try it in the Fall perhaps when things are a little cooler.

As for not using the battery to accelerate, I'll defer to the collective, but that doesn't make sense in my head... the traction battery provides "instant torque", starting from a stop is something it does WAY better than an engine that needs to rev to get power. And in my head I'm always thinking "you use that darn battery whenever you can, don't be saving it up because who knows if you'll get an opportunity on this run. If you deplete it to the extent that the engine needs to kick on, well so be it. You got your $'s worth." I understand using the engine.... to recharge the battery.... to drive the wheels may be less efficient that going directly from the engine to the wheels, but there are so man other opportunities to recharge the battery other than the engine alone with things like coasting downhills and very early, very light braking when coming to a stop to pump juice into that battery. So overall is it really that inefficient to "use that darn battery as much as I can"?

Maybe I'm thinking about it wrong, and I have no idea what others RAV4 Hybrid drivers are getting on the forum, nor their driving environment, but so far I'm happy, but can always do better! Thank you again.

https://photos.app.goo.gl/BXRdNndnvviZpGhH9
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Old 05-18-2019, 07:31 PM   #8 (permalink)
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OK, I think I understand the purpose of accelerating with the engine up to speed and then coasting with the battery as much as possible.

71F day, mostly rolling hills highway and then city to my house in moving traffic. Ran the A/C with a passenger at 73F. Tires were 50.5 PSI hot when I parked it:

https://photos.google.com/photo/AF1Q...LSjaalrHxDI8e8

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