Power mode for best milage

Pulse and glide is the king of MPGs. The "pulse" portion relies on heavy acceleration. It maybe counter-intuitive, but driving like a 100 year old grandma forcing it to stay in EV mode will lower your overall mileage.

 

You do not list a location, but some of the 'advantage' of Eco mode is going to be under A/C usage. Where I live, the last 3 months have not been the most A/C intensive of the year.

 

Pulse and glide is a lot easier with Eco than with Pwr. I haven't found any big differences in day to day driving beyond that. The A/C and fan issues do not play a big part where I live.

 

Depends on the situation. See my experiment at 2 Trip Pairs, With/Without Emphasis on EV | PriusChat

 

I haven't experimented with PWR mode yet. I started in Normal and then switched to Eco all the time. I've only used Power for going up a steep driveway at work. I'm going to try it tonight because I'm impressed by the MPGs I'm seeing reported here. I guess it's hard to make the switch because it boggles the mind how something with the name PWR could get better MPGs!

 

Is there a way to set PWR mode automatically when you start the car?

 

In a word, no.

 

It's all in how you drive the car. One mode is not more efficient than the other except for Eco Mode when using the A/C system heavily.

Some people claim to get better FE in Power Mode but it has nothing to do with the mode so much as how they use their right foot. I suspect those who get better FE in Power Mode are those who accelerate too slowly when using other modes. Applying more throttle in Eco Mode would achieve the same thing.

 

GEEEZZZ

there is no difference btw those modes only how "deep" you push the pedal !!!

It is only changes the coupling of the pedal !!! It is not even connected mechanically to any part of the engine/fuel system ...

Some other cars it is really means some engine performance mapping but by all data so far not in the prius !!!

 

I tried ECO mode and all I could tell happened is the accelerator seemed to need pushed harder to make anything happen, compared to the PWR mode or just not pushing any of the buttons. That said, I just ignore all three buttons and drive it in whatever the default is. I've been getting from 48 to 53 mpg doing this, 53k miles on Firestone FR710 tires that came on it when I bought it in February. My first tank was 45.89, using mostly ECO mode.

Then I found this web site and started accelerating to my target speed more aggressively. I've been much happier since I changed driving styles.

 

I'm wondering if power mode also changes the way the computer "mixes" and maintains the hybrid system. I've seen mentioned in another thread in this forum that PWR mode tends to try to keep the battery at a higher SOC more consistently. I am guessing having a consistently higher SOC may would be more beneficial because it gives the ICE a consistently higher available power assist from the traction motor. So, less gas is wasted for more torque and less time recharging.

It is also my guess that ECO mode, by the nature of the less sensitive accelerator, tends to favor the use of battery power longer as the main source of torque to get the car moving from a dead stop, resulting in a slower acceleration and faster SOC depletion. It is possible that ECO mode allows the system to allow a lower SOC before charging (I've not really tested that out to really know). If that's the case, there are two things that I would think would be unfavorable about ECO mode. 1) There is less available assistive power from the traction motor compared to PWR mode, and 2) there is more time required to recharge the battery, which isn't great from MPG either.

Could be wrong, but a theory that makes sense to me. This doesn't account for the help of regenerative braking. So, if you put that into the mix, I can see how it is still possible that things can even out between the two mode depending how how much regenerative braking would help recharge the battery over the ICE doing it.

 

I see many 'theories' about PWR, but all Toyota admits to is that compared to normal, they remap the throttle position to be more abrupt in the early part of the pedal travel.

 

so your theory is that toyota created the ECO mode which according to this theory less efficient ...

well that sounds far fetched to me

according to openly available information (I believe some coming from Toyota) only accelerator re-mapping happens besides small things like in ECO A/C power is reduced sligthtly and it allows ICE turn off a few dozen degree earlier there is one more which I can not recall now.

 

It is more efficient that all the energy from gasoline is converted into mechanical kinetic energy that move the car forward - in order to get the highest MPG performance possible. Of course this is not possible because the car must stop and vary its speed and it is subject to environmental factors like traffic lights and stop signs. Fuel Efficiency losses are greatest when all the chemical energy generated by the gasoline to make the car move is lost when the car comes to a dead stop. The greater the initial speed before the full stop - the greater the loss in energy inefficiency. Regenerative braking recovers 10% to 50% of that energy but most of the energy lost from braking is lost as thermal heat. So given the same stopping distance, a Prius coming to full stop from 50 mph is much less efficient than coming to a full stop from 25 mph.

PWR starts up the gas engine a tad sooner than normal or ECO mode. In a non-plug-in Prius, all energy from the high voltage (HV) battery is generated from gasoline burned as fuel. To get the highest fuel efficiency on a Prius - a driver should avoid putting the Prius in a situation where the Prius HV battery drops below 50% (3 bars) and the gasoline engine is automatically started to recharge the HV battery back up to 50%. Why? Because the energy conversion from gasoline to electric power is a lossy conversion and recharging event will cause the Prius' MPG to drop. In the ideal situation the HV battery should be only recharged by stopping or as excess energy captured by the car's movement. Why does the Prius recharge its HV battery when it falls below 3 bars (50%) and forces its MPG to drop? To extend the lifespan of the HV battery and thus make the Prius more reliable., that is to say -- the engineering compromise is that reliable transportation is more important than fuel efficiency. But why does the Prius allow the HV battery level to drop below 50% in the first place? The Prius' Atkinson cycle gas engine has a low power/torque at low speeds when accelerating from a dead stop so Toyota's engineers uses the Prius' electric motor to compensate for this weakness to make the Prius accelerate like a conventional Otto cycle gas engine car even at low speeds where it never goes fast enough to recharge the battery later on -- even if it means depleting the HV battery below 50% and thus lower the Prius' fuel efficiency. This means in extended stop-n-go traffic jams the Prius could deplete the HV battery power in a few minutes - thus causing auto recharging of the HV battery pack which lowers fuel efficiency. So how do you avoid recharging the HV battery? The solution is obvious - the driver needs to depend more on the gas engine(ICE) rather than the electric motors (MG1/MG2) during acceleration by using the PWR mode instead of the EV or ECO mode and pulsing the accelerator to initiate the ICE as soon as possible.. Depending on the driving scenario the energy needed for acceleration from a dead stop vary and normal and ECO mode can be perfectly adequate for accelerating in warm temperatures, flat dry roads, and downhill dry roads - but in cold temperatures, wet roads, uphill roads, and stop and go urban traffic - the Prius is better off using the gas engine for most of the work. Unfortunately, the power from the Prius Atkinson cycle motor isn't as quick at a conventional gas guzzler's Otto Cycle motor....