Do we have Toyota Engineer in PriusChat?

ukr2 · Feb 20, 2007

I've only driven my Prius for 2 weeks and I really like it.
Then I read how you have to Pulse & Glide to improve the mileage.
Then I read everyone's adding the EV button to keep the engine off on short trips.
Then I read other's complaining that using Cruise Control will NOT get the best results.

WHY???

Why isn't the Computer programmed to get the Best Results???
Even if you need a few modes to tell the computer what you want, like -
perform P&G at desired speed
keep the engine off if battery is above 20% SOC
use cruise control, but be efficieny

And Why must we feather the Accelerator or Brake to get our desired results -
Regen, but don't apply Friction brakes. More Regen. More Regen.
Increase speed, but don't enable the engine yet. Coast. More Speed, without engine.

This Computer, though pretty good, could be even better with some tweeks.

It's only Software !!!

AND
Has the Prius Software been changed over the years?
Have the older models been able to get upgrades?

If you have ever written performance software, you know it's possible to make it better.

efusco · Feb 20, 2007

Then I read how you have to Pulse & Glide to improve the mileage.[/b]
Click to expand...

You can P&G to improve gas mileage, but you don't have to do so...there are a number of techniques that will help.

Then I read everyone's adding the EV button to keep the engine off on short trips.[/b]
Click to expand...

I don't think there's any truth to that and can't imagine where you read it. Using the EV button can be helpful, but not to stay in electric for short trips. Again, this is a complex subject that you can do a search and find much information on.

Then I read other's complaining that using Cruise Control will NOT get the best results.

WHY???

Why isn't the Computer programmed to get the Best Results???
Even if you need a few modes to tell the computer what you want, like -
perform P&G at desired speed
keep the engine off if battery is above 20% SOC
use cruise control, but be efficieny[/b]
Click to expand...

The CC on the Prius is a standard CC at this time. It is not tied to the ECU so it's NOT a software issue. The reason it's not more efficient is b/c there's a slight delay as the CC realizes your speed has dropped below the set point then aggressively accelerates back to speed. It can't anticipate stops or hills or needs to speed up.

Also, the ICE had better be ON if your battery SOC ever gets to 20%. In fact you may not even be able to start the car w/ a 20% SOC. It's programmed to stay b/w 40-80% and rarely goes outside of the 50-65% range. Again, there's a lot of information out there on why this is, but suffice it to say it's to protect the battery from damage and prolong it's life.

And Why must we feather the Accelerator or Brake to get our desired results -
Regen, but don't apply Friction brakes. More Regen. More Regen.
Increase speed, but don't enable the engine yet. Coast. More Speed, without engine.

This Computer, though pretty good, could be even better with some tweeks.

It's only Software !!!

AND
Has the Prius Software been changed over the years?
Have the older models been able to get upgrades?

If you have ever written performance software, you know it's possible to make it better.[/b]
Click to expand...

While it might seem a simple thing on the surface, it isn't. How is the car supposed to know whether to shut down the ICE when you slow down a little bit....maybe it's a temporary slowing for traffic before you go back up to speed. If the ICE shut down you pay a cost in electrical energy to restart, it takes away from the smoothness of the operation of the system and people will complain about the jerky ride.

Now, that said. It's possible that the next generation Prius will be able to do a little better. The NAV may be tied into the ECU with terrain mapping to anticipate terrain and traffic conditions thus telling it when to expend more battery power or to conserve it in anticipation of need. But this is very far from simple programming and it still won't affect the cruise control.

I think the part you're missing is that the car can't anticipate what you're going to do, what the traffic is, etc. Without that it's impossible to program the car to do what you want when you want...so they picked averages and what they thought would be most likely for most conditions.

member · Feb 20, 2007

<div class='quotetop'>QUOTE(ukr2 @ Feb 20 2007, 08:18 PM) [snapback]393664[/snapback]</div>

I've only driven my Prius for 2 weeks and I really like it.
Then I read how you have to Pulse & Glide to improve the mileage.
Then I read everyone's adding the EV button to keep the engine off on short trips.
Then I read other's complaining that using Cruise Control will NOT get the best results.

WHY???

Why isn't the Computer programmed to get the Best Results???
Even if you need a few modes to tell the computer what you want, like -
perform P&G at desired speed
keep the engine off if battery is above 20% SOC
use cruise control, but be efficieny

And Why must we feather the Accelerator or Brake to get our desired results -
Regen, but don't apply Friction brakes. More Regen. More Regen.
Increase speed, but don't enable the engine yet. Coast. More Speed, without engine.

This Computer, though pretty good, could be even better with some tweeks.

It's only Software !!!

AND
Has the Prius Software been changed over the years?
Have the older models been able to get upgrades?

If you have ever written performance software, you know it's possible to make it better.
[/b]
Click to expand...

I agree with what Efusco wrote, but in addition...

Toyota sells the car to "the market", which on average is comprised of people who want to press on the gas pedal and go. If they were to program in P&G, the average driver would immediately take it to the dealer complaining that their "car is pulsing and gliding!"

The techniques people use to get the best gas mileage are done at the expense of things like speed and acceleration, things many people don't want to lose.

ukr2 · Feb 22, 2007

Evan and "Display Name",

Do we have a Toyota Engineer in PriusChat?
I'd enjoy hearing from a Company man about the logic behind the Prius, step-by-step.

I didn't say everyone had to select P&G.
But if P&G can improve mpg, and if you had the ability to select P&G mode, wouldn't you?

And don't we have a lot of posters talking about installing an EV button, and some worrying if it voids the warrenty or not? If there is any advantage in using the EV button, why didn't Toyota make the factory button available to North America? If the advantage of the EV button was, instead, part of the Prius Software Logic, noone would have to install it. We all would get its advantage.

And if the CC on the Prius is a standard CC at this time, WHY didn't Toyota tied it to the ECU to make it a software issue?

All of these questions are best answered by a Toyota Insider. Drivers of the Prius, no mater how experienced, don't have the answer. We can only Guess.

efusco · Feb 22, 2007

<div class='quotetop'>QUOTE(ukr2 @ Feb 22 2007, 07:05 PM) [snapback]394931[/snapback]</div>

Evan and "Display Name",

Do we have a Toyota Engineer in PriusChat?
I'd enjoy hearing from a Company man about the logic behind the Prius, step-by-step.

I didn't say everyone had to select P&G.
But if P&G can improve mpg, and if you had the ability to select P&G mode, wouldn't you?

And don't we have a lot of posters talking about installing an EV button, and some worrying if it voids the warrenty or not? If there is any advantage in using the EV button, why didn't Toyota make the factory button available to North America? If the advantage of the EV button was, instead, part of the Prius Software Logic, noone would have to install it. We all would get its advantage.

And if the CC on the Prius is a standard CC at this time, WHY didn't Toyota tied it to the ECU to make it a software issue?

All of these questions are best answered by a Toyota Insider. Drivers of the Prius, no mater how experienced, don't have the answer. We can only Guess.

[/b]
Click to expand...

Well, if we have an engineer from Toyota who's involved with the Prius he's never made him/herself known. So you're stuck with us.

If you look at the info on the new Highlander Hybrid (2008) it will include an ECON button...I don't think it will pulse/glide but rather will aim at keeping the car in it's most efficient rpm band based upon battery SOC. A built in P&G, again, would be difficult or impossible due to the lack of ability to anticipate terrain and the fact that the degree of P&G could be a danger to surrounding traffic....it is a task that can only safely be accomplished by a human.

The reasons for no EV button in the US have mostly been speculated at. However one member has had the opportunity to speak to a Prius Engineer and found that at least part of the answer was related to concern about emissions secondary to cooling of the catalytic converter if used inappropriately. It seems pretty clear from all we've been able to gather over the last 3 1/2 years that we've been researching this through all available resources that the complexity of getting the EPA to approve the EV button in the US was the main thing that prevented it's being included.

The other reasons, again, are well detailed in multiple threads but clearly include the ease of LOWERING FE if misused. That said the fact that it will be included in the '08 Highlander Hybrid suggest the prior concerns have been addressed and that the emissions issues resolved. I expect clear guidelines to the efficient use of an EV button will be included. And, again, it can't be part of the logic b/c the car can't predict or anticipate the best times to go into EV mode. I can't think of a better way to explain that...if you got in my car with me I could demonstrate in about 15 minutes, but there are conditions that the only advantage is when the human driving can predict the future by knowing what the traffic conditions are, where the lights are, what speed you'll be going, etc.

Same thing w/ the CC, if you read my post....the reason is b/c no CC can anticipate terrain or traffic.

I'm sorry I'm not a Prius engineer, but you should take the time to research these issues in prior threads and try to give some credence to those of us who've been asking these questions for 3 1/2 years and sought out the answers. Much of the info is in technical reports done by Toyota and others, much is logic based upon experience, and much is accumulated info from many other places. We know what we're talking about.

ukr2 · Feb 22, 2007

Evan,

Thanks again. I know I ask a lot of Why's and Why Not's. It's the engineer in me.

PriusChat is lucky to have dedicated folks, like you, to assist us newbes.

Also Toyota recognizes the efforts of PriusChat by listing it on the top of its Hybrid Synergy Drive - related sites -
http://www.toyota.com/vehicles/minisite/hy...ANDING_MINISITE

By the way, what is your speciality as an MD?
Or does your MD not mean Medical Doctor ???

efusco · Feb 22, 2007

Emergency Medicine.

tomdeimos · Feb 23, 2007

Pulse and glide is optional and helps with any car using a gas engine. It works better in a Prius because the engine can be off, but you would not want the car doing it all the time on its own. I virtually never pulse and glide myself and have gotton a full tank at over 60 mpg.

I have the EV button and it helps a lot in some situations but short trips are not it.
I understand we'll have the button in the next version.

Cruise control is bad because it is designed to keep speed constant. This is not best for economy especially when cresting a hill where you will need to brake on the down side, but that is what most people expect cruise control to do.

The computer is programmed to give you the best possible results. There are some limitations to this that we can take advantage of: We can see what is coming or plan what we want to do next and the car can't know these things. Secondly the car must have some hysteresis around it's operating point to prevent oscillation. That is why we can get to the peak economy when done accelerating by feathering the pedal a bit. There's the same hysteresis with the engine on off switching so we can do a lot to control that too and stay in battery mode without the ev button quite often.

Adding a button for more economy has been rumored for the next model.

I really don't see them fixing the cruise control to do pulse and glide. There's just too many ways to do it with terrain effects that even a nav hook up won't likely handle, as well as traffic issues. When cruse control can do this we won't need to drive as the car should be able to do that too.

You need some practice and you can do all the things you mention regarding regen vs friction brakes,
controlling engine on, coasting. If you add a Can View you'll find it much easier. Worth it just for the ice-spin indicator alone.

And the Prius software has been changed a lot over the years. My car is far better now than when I got it. I've only had one software upgrade but it made all the difference I needed for my driving. But they have to save some improvements for the next model which should get a big boost in economy.

ukr2 · Feb 23, 2007

P&G takes practice at feathering the accelerator to get it to Glide.

Wouldn't it be nice to be able to push a "Glide" button or pull the CC handle, like Cancelling", to Force the Prius to stop energy flow ???
Then to Glide would be easier.

Now there's an Option I'd implement?

Who can find out how to do it?

squall · Feb 23, 2007

<div class='quotetop'>QUOTE(tomdeimos @ Feb 23 2007, 07:36 AM) [snapback]395097[/snapback]</div>

Pulse and glide is optional and helps with any car using a gas engine. It works better in a Prius because the engine can be off, but you would not want the car doing it all the time on its own. I virtually never pulse and glide myself and have gotton a full tank at over 60 mpg.

I have the EV button and it helps a lot in some situations but short trips are not it.
I understand we'll have the button in the next version.

Cruise control is bad because it is designed to keep speed constant. This is not best for economy especially when cresting a hill where you will need to brake on the down side, but that is what most people expect cruise control to do.

The computer is programmed to give you the best possible results. There are some limitations to this that we can take advantage of: We can see what is coming or plan what we want to do next and the car can't know these things. Secondly the car must have some hysteresis around it's operating point to prevent oscillation. That is why we can get to the peak economy when done accelerating by feathering the pedal a bit. There's the same hysteresis with the engine on off switching so we can do a lot to control that too and stay in battery mode without the ev button quite often.

Adding a button for more economy has been rumored for the next model.

I really don't see them fixing the cruise control to do pulse and glide. There's just too many ways to do it with terrain effects that even a nav hook up won't likely handle, as well as traffic issues. When cruse control can do this we won't need to drive as the car should be able to do that too.

You need some practice and you can do all the things you mention regarding regen vs friction brakes,
controlling engine on, coasting. If you add a Can View you'll find it much easier. Worth it just for the ice-spin indicator alone.

And the Prius software has been changed a lot over the years. My car is far better now than when I got it. I've only had one software upgrade but it made all the difference I needed for my driving. But they have to save some improvements for the next model which should get a big boost in economy.
[/b]
Click to expand...

<div class='quotetop'>QUOTE(tomdeimos @ Feb 23 2007, 07:36 AM) [snapback]395097[/snapback]</div>

Pulse and glide is optional and helps with any car using a gas engine. It works better in a Prius because the engine can be off, but you would not want the car doing it all the time on its own. I virtually never pulse and glide myself and have gotton a full tank at over 60 mpg.

I have the EV button and it helps a lot in some situations but short trips are not it.
I understand we'll have the button in the next version.

Cruise control is bad because it is designed to keep speed constant. This is not best for economy especially when cresting a hill where you will need to brake on the down side, but that is what most people expect cruise control to do.

The computer is programmed to give you the best possible results. There are some limitations to this that we can take advantage of: We can see what is coming or plan what we want to do next and the car can't know these things. Secondly the car must have some hysteresis around it's operating point to prevent oscillation. That is why we can get to the peak economy when done accelerating by feathering the pedal a bit. There's the same hysteresis with the engine on off switching so we can do a lot to control that too and stay in battery mode without the ev button quite often.

Adding a button for more economy has been rumored for the next model.

I really don't see them fixing the cruise control to do pulse and glide. There's just too many ways to do it with terrain effects that even a nav hook up won't likely handle, as well as traffic issues. When cruse control can do this we won't need to drive as the car should be able to do that too.

You need some practice and you can do all the things you mention regarding regen vs friction brakes,
controlling engine on, coasting. If you add a Can View you'll find it much easier. Worth it just for the ice-spin indicator alone.

And the Prius software has been changed a lot over the years. My car is far better now than when I got it. I've only had one software upgrade but it made all the difference I needed for my driving. But they have to save some improvements for the next model which should get a big boost in economy.
[/b]
Click to expand...

i am a new owner with about 1,700 on a 2007 touring model Prius. I am getting 40 MPG. That is 20 less than you have gotten on one tank. I am not looking for 60. I am looking for 45-47 MPG average. but i do not understand why i am getting 40. i am not an agressive driver with the car. I am mindfull of the concept of P&G even though i dont think i actually practice it regularly. I have not checked my tire pressure but the car is only 1 month or more old. the temperature here in Seattle has been a bit chilly, averaging about 38-49 during the period i have owned the car.

I cannot figure why i am getting this low a milage and i took one long trip during this time, (290 miles each way, again in cold weather, and i did use cruise control) and still have not gotten better than 40.7 on any tank.

Any ideas?

efusco · Feb 24, 2007

<div class='quotetop'>QUOTE(ukr2 @ Feb 23 2007, 09:26 PM) [snapback]395615[/snapback]</div>

P&G takes practice at feathering the accelerator to get it to Glide.

Wouldn't it be nice to be able to push a "Glide" button or pull the CC handle, like Cancelling", to Force the Prius to stop energy flow ???
Then to Glide would be easier.

Now there's an Option I'd implement?

Who can find out how to do it?

[/b]
Click to expand...

Another long discussed idea...and a popular one. I'd still like one even though I can get into a glide without looking or really even thinking about it now it would still be nice.

local_host · Feb 24, 2007

<div class='quotetop'>QUOTE(squall @ Feb 23 2007, 10:15 PM) [snapback]395635[/snapback]</div>

I cannot figure why i am getting this low a milage and i took one long trip during this time, (290 miles each way, again in cold weather, and i did use cruise control) and still have not gotten better than 40.7 on any tank.

Any ideas?
[/b]
Click to expand...

It might be because it still needs to be fully 'broken in' (which is supposed to about 6 months to 1 year)? Also, from what I've read on this forum, warm weather results in better gas mileage than cold.

By the way, how are you driving the Prius? I notice that if you 'tap' the accelerator after getting up to speed, the mpg improves. For example: when merging onto the freeway, get up to 65, then let go of the gas and just lightly hold it down. This 'release' seems to help out mpg, as opposed to just holding down the gas without letting go- once up to desired speed (which keeps the ICE on at full?)

tomdeimos · Feb 24, 2007

<div class='quotetop'>QUOTE(squall @ Feb 23 2007, 11:15 PM) [snapback]395635[/snapback]</div>

i am a new owner with about 1,700 on a 2007 touring model Prius. I am getting 40 MPG. That is 20 less than you have gotten on one tank. I am not looking for 60. I am looking for 45-47 MPG average. but i do not understand why i am getting 40. i am not an agressive driver with the car. I am mindfull of the concept of P&G even though i dont think i actually practice it regularly. I have not checked my tire pressure but the car is only 1 month or more old. the temperature here in Seattle has been a bit chilly, averaging about 38-49 during the period i have owned the car.

I cannot figure why i am getting this low a milage and i took one long trip during this time, (290 miles each way, again in cold weather, and i did use cruise control) and still have not gotten better than 40.7 on any tank.

Any ideas?
[/b]
Click to expand...

To get 60 you have to work at it. 40 may be very good depending on how you drive and where you are.
I've had tanks as low as 40 too, here it happens when weather gets down to 0 degrees F with my short commute.

To get your max you want a good route where you can coast some down hills, and best to have longer down grades and steeper up grades. Then you want one where you can safely drive around 35 to 40 mph with temperatures around 80 to 85 degrees F. With this kind of driving some people can get over 70 mpg.

I think probably everyone that gets over 70 mpg is adding in pulse and glide too.

You're on the west coast and my impression is everyone out there drives dangerously fast. Here maybe 20% of drivers do so, but there are still plenty going close to our low speed limits, which helps.

If you drive at 70 mph or over and weather is cold you won't get 60 mpg and you may not get in the 50's.
Read up on the subject here. Just warm weather and summer gas alone should boost your mpg by over 10 mpg when driving fast and you don't have to do anything different.

darrylp · Feb 26, 2007

<div class='quotetop'>QUOTE(efusco @ Feb 20 2007, 09:37 PM) [snapback]393679[/snapback]</div>

The CC on the Prius is a standard CC at this time. It is not tied to the ECU so it's NOT a software issue. The reason it's not more efficient is b/c there's a slight delay as the CC realizes your speed has dropped below the set point then aggressively accelerates back to speed. It can't anticipate stops or hills or needs to speed up.

[/b]
Click to expand...

In my book this IS a software issue. The GPS internally knows altitude at the present location and the map software can know the altitude ahead. This could be integrated into the cruise control.

Isn't there some car that has a "learning" feature? First time on a route it knows nothing about the hills but after a trip or two it knows it is approaching a hill or valley and can begin to compensate. This would be particularly economical with a CC that was programmed for max MPG atr a set speed.

You listening, Toyota???

Do we have Toyota Engineer in PriusChat?

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