Suggestion to Toyota engineers: Glide mode button on steering wheel

Basically the same thing as neutral w/o shifting back in to D?

 

PriusCinBlack I think you are on to something. It would be a great feature to making hypermiling easier and might even convert some non-milers.

 

I had thought of it weeks ago.. but in the end, found the idea to be impractical... didn't bother ever mentioning it because of that.

over 45 mph, the ICE turns on to protect MG1.. barely any fuel or not, it's running.

my idea was to implement something that would apply the correct amount of throttle to cancel out the regen.. which would be a safer alternative than a button that cuts the ICE and somehow find a way to have the car not regen... sounds like a bad idea.

 

i suppose one reason they have the slight regen when you let off the gas is for liability reasons. most people expect engine braking when you let off. so if someone new to hybrids lift off and all of a sudden the car doesnt slow down as fast as they expect...

i've thought about a mode (on the shifter like B mode, or a separate button like EV mode) where you can turn off the slight regen and can glide effortlessly by simply letting off the gas pedal. but again, liability reasons perhaps?

and yes the ICE will have to turn on to protect MG1 at some point, but that's not the issue. the issue is that P&G can only be achieved with a conscious effort. with practice it becomes second nature, but why doesnt toyota make it an official mode? i admit, as a new hybrid owner, i sometimes catch myself looking at the power meter, vs the road, more often than i should, just to see if im gliding. the stupid location of the gauges doesnt help either. if toyota made it an official mode, then i'd not even have to think about it...

 

well.. P&G was something.. that someone found out to help in achieving better mileage in a hybrid..

yes, the slight regen is there for people who expect the car to slow down when you let off the gas... and it also acts as a way to ensure the traction battery gets a nice trickle charge.

perhaps it's a liability thing.. but indeed i would say it would be rooted as a safety concern... you should always be conscious of what you are doing with the vehicle while driving... so what does it matter then if there's a button that helps you glide easier? the amount of attention you are supposed to have on the road remains the same.

the truth of the matter is.. there are too many variables to be able to engineer something like that and keep it safe.

so what about the people who can't glide at all? Wayne Gerdes just have people shift into neutral.. oh my goodness!! isn't that the easy button you guys were looking for?

ok.. another fact is, you can pretty much only glide (as in a true glide with the ICE not running at all).. under 45 mph.. and for also those reasons... using neutral should be fine... obviously unless you're going downhill and speed up beyond that while still in neutral.

P&G isn't something Toyota made up.. nor would they probably endorse because of the possible safety concerns... so I can't see why they would make a mode or button.. or anything of the sort for us hypermilers..

it's almost like asking... why didn't Toyota do a full boattail on the vehicle.. knowing very well the drag would be significantly reduced?

 

From what its worth, I read that Toyota designed the Prius so that it would slowdown by itself if the accelerator was not pressed so the Prius drive more like a regular car (and hence be an easier car to drive as well as a safer car for most drivers and thus an easier car to market and sell). This particular design feature is suppose to make a *runaway* Prius unthinkable which is why the so called *runaway* Prius affair in the USA (circ. ?2007-2010) caught Toyota off guard.

Toyota's premise that most drivers would drive the Prius like a regular car ( and would NOT learn and use new driving skills like P&G) has been right on the money sofar.

Gliding is not something that the driver can demand at any time. Gliding is like sailing, the environment dictates whether it is possible or not. One cannot sail the seas without a wind. One cannot glide on a road without the right driving conditions. The OP basically is having a problem modulating the accelerator so that the regen brakes are not ON and the electric motors are running at very low levels or not running. I would prefer a programmable audiable chime (that would go on when the ICE is off, when the electric motors are in low power or off, AND when the regenerative brakes are off) which can signal a driver that the Prius is now gliding - that way the driver could keep his/her eyes on the driving conditions so he/she can extend the glide phase as long as possible.

The Prius automatically shuts down the gas engine (so it doesnot have to be done manually) to save gas which is the main energy saving component to the hypermiling technique Force Auto Stop/Shutdown (FAS) while driving and during idling ( aka stop-idle technology) - making the Prius one of the easiest cars to hypermile.

It's illegal in about half of the states of the USA to shift your vehicle's transmission into Neutral while the vehicle is moving downhill, i.e. half the states of the USA says that the hypermiling technique known as Neutral Internal combusion Engine (NICE) is illegal while going downhill ( but it is still legal going uphill in most states). NICE eliminates the minor internal resistance of the motor and tranny during the glide phase. Most drivers won't notice the any extra difference in distance travelled by switching to Neutral unless the the Prius is gliding for an extra long time (and the Prius would have to slowdown to an unusally slow velocity that most drivers would not tolerate) with the tires over inflated.

IIRC Boattailing the already aerodynamic Prius can increase fuel efficiency by about 15% at highway speeds 55 mph and greater ( for pickup trucks boattailing can provide even more dramatic MPG improvements... e.g. 14mpg ==> 28 mpg). Ecomodder.com has documented atleast one prototype/example in the USA of 2nd gen Prii being modified in this way. The main disadvantage to this modification was the loss (lack) of access to the rear hatchback/cargo area.

Just as effective aerodynamic design strategy would be to decrease the frontal surface area (which is what Honda did when adapting their 2nd generation Honda Insight aero design from the Toyota Prius aero design). Interestingly, while the 2nd generation (>2010) Honda Insight normally gets worst MPG( about 42 mpg) than the 3rd generation (>2010) Toyota Prius (about 50 mpg), a hypermiled +2010 Honda Insight can get about 8 mpg better (about 73 mpg) than a hypermiled +2010 Toyota Prius (about 65mpg) in a hypermiling marathon. The 2012 Prius c has a decreased frontal surface area and should be able to beat a 2012 Honda Insight in a hypermiling marathon.

 

The button could be very easy much like cruise control, when you activate it it's on until you hit the brakes. If the cruise control is not safety hazard then this button can't be a hazard.

 

I haven't looked at the throttle pedal assembly on the Prius C's yet, but if it's anything like my old Yaris:
The throttle pedal on a modern car is just a potentiometer (pot for short, aka variable resistor). The ECU simply reads the voltage drop (from +5v) of the pot at any given point in time.

A "glide" button could be as simple as an additional pot on the dashboard (for adjustability) and a button on the steering wheel to complete the circuit.

I don't recommend that route, because in practice this is dangerous. You could set a throttle position and the throttle could get stuck "ON". The best solution would be a small microcontroller to control everything. It would take a reading the current position of the throttle pedal and brake pedal, if there is a change it would turn off the control circuit. Then, you could use a digital pot controlled by the microcontroller to handle the throttle adjustment. The brake pedal should be a "hard" override, cutting power to the circuit if the brake pedal is pressed (just as an example).

Just a thought.

 

funny enough VAG/Porsche has a "glide" mode. in the cayenne hybrid, there is a "Sailing" mode that disconnects the ICE from the motor and transmission to prevent engine braking and thus "sailing". i do not know if they use slight regen when "sailing" but still, the idea that a manufacturer wouldnt do this has been disproved. its just that Toyota wont do this...

and this "sailing" mode is only for hybrids right? wrong...

i still think there should be a dedicated position on the shifter or a dedicated button to enter "glide mode".

 

well... i suppose i can go back to the drawing board and see what i can come up with..

i'm already used to doing it with my foot.. but i can try making an "easy button"..

the only thing i really need to figure out.. is at different speeds.. at least for me.. it feels as if i need the gas pedal at a different position to keep the car gliding... so if that variable isn't constant... then there are other things I need to take into account..

 

hence the "need" for an easy button. we know about P&G because we are "hybrid enthusiasts". but the run of the mill prius buyer is largely unaware of this "secret technique" and so i find it odd that toyota never chose to exploit this "feature" like VAG/porsche has...

toyota should have made it an opposing mode for the oft confusing and mysterious B mode. in fact if we had this glide mode, regular people may intuitively catch on to what B mode actually does. one mode makes you slow down faster when you lift off the throttle, and the other mode lets you freewheel. its something very intuitive to understand once you have both modes...

 

Hi Squall, i'm happy to see you changed your mind since last time we talked about the subject

Yes, Madfast the system of sailing applied by Porsche should really be implemented by Toyota, but sadly the gearbox is involved and the HSD system cannot be fitted as it is with such a system, for the same reason of the speed limitation in "N", it will overrev the MG.
As a side note, the Porsche system (i do believe also MB uses it) is electronic controlled and gives a full "sailing" with no engine regen, if the car is on a straight line and it does react immediately releasing engine brake effect as soon the wheel should suddenly turn or if the stability of the car is compromised by any event.
This is what i've been told, it should be some documentation about it.
Now, that's THE system!

 

well obviously it wont be the same as the hybrid systems are totally different. but the idea is the same. right now, you have to physically depress the throttle a little to cancel out the slight regen. i propose a mode where the car simply does that for you. yes above a certain speed, the ICE will have to spin to protect MG1, but it doesnt necessarily have to use any fuel. that is the so called "warp stealth" mode. i'd like to see a mode where the car does this all by itself upon lifting off the throttle...

 

Well Madfast, carefully thinking, the simplest modding could be a button that say to the software to do not engage engine regen when the throttle is closed and voilà, you get freewheeling.... I'm wondering if that can be accomplished by some expert user....

Speaking of Toyota, the same software tweak can be made in no time, but to avoid any misuse, avoiding the button and allowing the software to eliminate engine regen only when the car parameters are ok, like the Porsche solution. The Stability Control System could easely give the consensus.
More carefully thinking, it's a shame that a similar simple software modification is not already there..... hardware cost: not even a cent..

 

If not a button - a symbol to show that you're gliding would also be useful.

 

To accomplish the equivalent of feathering the accelerator to eliminate gas pedal regen, would a possible solution to this be the insertion of a few strategically placed shims in the pedal stop such that the accelerator pedal ends up in a slightly depressed position when released by the driver. The adjustment of the thickness or the number of shims would determine how much regen if any is applied. This eliminate having a button. What I don't know is if this very slight displacement of the gas pedal would have any unintended consequences.

The other thing I was thinking of was the placement of a 3 pedal resistance springs offset at three different positions that enter tension at at points corresponding to different amount of angular pedal displacement, with each displacement point requiring progressively stronger pedal pressure. The 3 displacements would correspond with 1. the transition from EV to ICE Eco region, 2. the transition from Eco ICE region to PWR region and 3. from PWR region to beyond PWR region. This last area would have the strongest spring resistance force to discourage going beyond the PWR region without strong foot pressure.

My experience right now is that I find that I have to keep my eyes on the HSD Indicator display to see if my pedal position has not changed after going over a bump for example, plus it can be tiring on a long trip to hold these positions for extended periods. The tactile feedback of the step up in spring tension at these positions, I believe would considerably improve driver foot comfort when implementing hypermiling techniques.

 

An unintended consequence that comes to mind is slower responsiveness when it comes to required acceleration, but the amount of required forced could be learned for those times when responsive acceleration is needed (i.e. entering a freeway from a short on-ramp).