Gen5 Hypermiling Checklist

First things first: gonna need a display that measures MPGs in the 100's. I'd been disappointed with the standard trip summary shown when turning the vehicle off. It maxed out at 99.99...

Good news! There's another MPG gauge, and it reads to 199.99!!!

Go to your multimedia display ("B" on pg. 102 of manual). Touch the car icon, then Trip Information, then the History tab. On this screen (pg. 105), you'll need to hit update every time you want to measure your MPG's (up to 199.99) on a single trip. If you don't hit update again at the conclusion of your trip, I believe it will continue to measure your MPG's for the rest of the day. A new recording (bar) will be created the following day, or whenever you hit update again (whichever comes first).

 

So far I've only used it for individual trips. Gotta hit update each time before you pull away.

 

https://www.greencarreports.com/news/1139900_how-to-get-more-mpg-out-of-your-toyota-hybrid

"From Green Car Reports’ experience with a wide range of test vehicles—nearly all the hybrids in the Toyota/Lexus lineup—using Eco mode results in a difference that you likely won’t notice after the first few minutes. It encourages smoother driving in most cases, and you’ll notice a payoff at the pump."

"The system draws from vast data maps, looking at various parameters (some predictive) to decide when to run the engine and when to rely only on the electric motors.

Bottom line: Toyota hybrids are already optimized for efficiency to the point that almost anything you change, except for slowing and smoothing your driving habits, and running in Eco mode, is likely to cut mpg. And that includes using EV mode."

This is why I will sometimes get marvelous fuel economy in the Prius while on a phone call. I'm simply not thinking and just letting the computer do the work.

Usually while on a call I'm driving very passively also, and perhaps even a bit slower. I will say though, there are improvements to be had in the Prius that are additive to the car's onboard "AI".

One of them is trying to keep the gas pedal very stable when gliding with ICE off. Don't try (excessively) to keep the engine from coming on (eg. super slow starts), but also don't trigger the ICE with sloppy pedal work (eg. accelerating past the halfway line on the Eco guide when you didn't have to in order to maintain cruising speed).

Driving as smoothly as possible, while interpreting traffic light behavior ahead - deciding whether to glide/coast (without EV or regen braking), and hoping for a green light and traffic to clear; accelerating to make a stale green light, or admitting defeat and using regen breaking to reclaim as much lost energy as possible while stopping, are the main practical ways you can augment your cars fuel economy.

Stopping/slowing a car's momentum is truly the enemy of fuel economy. The Prius just gives us a few tools to minimize the damage. Likewise, we're given tools to maximize the benefits of smooth driving.

 

I don't know where to put this exactly, but it applies to hybrid driving, hypermiling, and basically increased fuel mileage on the G5 in general. So here goes:

I've noticed during my month or so of driving the G5 LE, that battery levels appear to recharge faster and last longer than my G4 LE. I know they increased the battery size by some measure (was it +18%?). But when the car gets charged up to 4-5 bars, it shuts off really quickly and seems to let you glide longer (ICE off). Then when accelerating from a stop, adds a bar back quicker than I remember in the G4.

It also seems like average fuel economy when the ICE is running is worse than the G4. This makes perfect sense as it is more powerful and has a larger displacement than the G4. This would also explain why the battery seems to charge faster during ICE-on (more ICE power should generate a more powerful charge).

I think that accelerating to your desired cruising speed as fast as possible (within reason), and allowing the ICE to shut back off, is A key to maximizing your MPGs when you will have a long glide off-ICE once you get to that speed.. Following the Eco guide is fine, but I think there's a bit more fuel economy to be gained in the aforementioned scenario. If you are hitting light after light after light however, then accelerating faster than the Eco guide says, will probably harm your overall MPGs. In fact, I would try to trigger the ICE starting as little as possible when you are in downtown traffic with 20ish MPH speed limits and such. The ICE is a gas guzzler, so ideally you want it off unless you are doing a full acceleration.

But as mentioned in the prior post and quoted article: "Toyota hybrids are already optimized for efficiency to the point that almost anything you change, except for slowing and smoothing your driving habits, and running in Eco mode, is likely to cut mpg." This is an important point to always keep in mind. The G5 is VERY smart, and the way it cuts the engine off is different than the G4. I am only adding my experience for the Hypermiling Nerd in some of us who want to see if we can exceed the G5's MPG AI. There will come a time (it may already be here), when we no longer can beat the computer. At that point, the Prius MPG game is over. Just follow the rules.

 

Disregard some of the comments in the article that pertain to "EV mode". He's actually addressing the remaining Prius drivers out there who drive non-Primes yet still actually hit the "EV" button thinking it does something.

 

For me in the G4, a light pedal was far more useful than the EV button. And if I had a full charge, I could even stay on battery all the way up to city cruising speed. The G4 truly was the pinnacle of Prii when it came to pragmatism, utility, and reliability.

And then they decided to flex a little with the G5.

 

https://ownersmanuals2.com/toyota/prius-2023-owners-manual-86991/page-185

https://ownersmanuals2.com/toyota/prius-2023-owners-manual-86991/page-186

"EV drive mode’s possible driving
distance ranges from a few hundred
meters to approximately 0.6 mile (1
km). However, depending on vehi-
cle conditions, there are situations
when EV drive mode cannot be
used."

Pretty vague. I'm guessing it's just as useful in 2023 as it was in prior years (like tits on a boar).

Light pedal > "EV Mode"

 

I sense the "range" or gliding ability (ICE off) is 50% greater in the G5 than the G4. I also sense the ICE burns about 50% more fuel in the G5 vs G4 when running. This is not scientific data, just an educated opinion. It also aligns neatly with the facts that the G5 has 60% more HP than the G4 and still gets close to the same MPG's. The hybrid system MUST be more efficient right? With weight staying the same and wheels getting larger in every trim?

At 4-5 bars, I can "cruise for days" in the G5 on level surfaces compared to my G4.

 

I may have to change my opinion slightly on the EV Mode button. I used it last night at a spot where I have to drive up a fairly steep ramp before parking. I normally just feather the pedal trying not to needlessly fire the ICE.

It's been the case, that if I have at least 4 bars I'm good. In the G4, I could usually make it up on battery if I had a solid 3 bars. I think my effective gear ratio is higher with the 17's on the G5 versus the 15's on the 2019.

Last night I clicked the EV button and drove fairly carelessly up the ramp without the ICE coming on. The acceleration meter was a decent amount past the midline of Eco. Of course I was going very slow, but just the throttle position would kick the G4 off the EV Mode. I'll continue to test if the button has any EV holding power beyond pedal feathering. This would be useful.

 

I think there's more to it than just a larger battery. Today I was trying to pay attention to more things happening - specifically the times when the ICE was running and when it was not.

Like the G4, the EV icon displaying, is not perfectly synchronized to when the ICE shuts off. You've got to be looking at one of the gauges that shows the instant MPG. When it hits 100, the ICE is off.

Focusing on that today, I noticed the ICE shutting off VERY quickly after accelerating to speed. It seems more aggressive than my G4. This is in 100F heat index and heavy traffic. I really think the batteries are charging faster, and decharging slower also. Perhaps there's new technology in the charging system. The higher HP will help, but at a fuel cost.

I also focused on the trip history, the 5m bars that show MPG. During consecutive ICE cycles, MPGs suffer greatly - like under 25 MPGs at times. I'll try to get some photos of these "cycles". If they're happening during a trip with a bunch of stops, fuel mileage gets ugly.

I did use the EV button again when driving up the steep ramp. No ICE and I kinda tried to make it come on. I was at 4 bars. I wanna try it with 3. I think I'll get a "battery too low" rejection.