Underclocking the Prius and other Hybrids

Mardikes · 04-28-2006, 12:26 PM

After owning a 2001 Prius and a 2002 Prius, we sold both and bought a 2006 Highlander Hybrid and have on order a 2006 Prius.

I find that in driving the HiHy, that one really has to watch the acceleration. The car has incredible power, but more than we want or need. The single most important factor for me for MPG is how heavy my foot is.

These vehicles are bascially computer driven. When I put my foot on the gas, it is not mechanically increasing the gas, but instead inputting information to the computer to increase speed.

The computer already limits the maximum speed one can drive.

It also limits the maximum torque of the combined power to avoid destruction of the transmission, which basically is a limitation on maximum acceleration.

It seems to me that it would be easy to basically reprogram the computers to reduce that maximum acceleration.

One would need to limit the maximum acceleration from both the engine and the motor, otherwise the computer would put excessive strain on the battery and motor system instead of the engine.

It seems to me that this would possibly increase MPG. I am sure it would for the HiHy, probably less so for the Prius.

In essence, similar to computer that can be modified to make them faster -- overclocking-- we would be modifying the hybrid to make them slower, at least as to acceleration -- underclocking.

Now Toyota might not like to do this. For example, if someone does not know the vehicle is underclocked, then the person driving may not be impressed with the potential power of the vehicle. To solve this one might have a warning on the dashboard stating that the vehicle has been underclocked by the owner.

If this is possible, it might make sense for the Sierra Club, National Resources Defense Council and other green groups to lobby Toyota to allow these modifications.

Thoughts?

George

P.S. I would prefer to focus this posting on the technological issue of whether the reprograming could be done, not alternative work arounds, like being more careful at driving (I cannot control all of the drivers in our family) or using cruise control (not realistic in the city).

Frank Hudon · 04-28-2006, 12:30 PM

cheaper and easier and no potential problems is to reprogram your foot.

mikepaul · 04-28-2006, 12:43 PM

I use the cruise control as often as possible, highway or not. I rarely see where my foot does better. Maybe there are horror stories of old-school cruise sticking and causing accidents, but with throttle-by-wire that hardly seems an issue.

I say stick with as much computer control as you can, and hope for improvement...

highroute · 04-28-2006, 12:44 PM

<div class='quotetop'>QUOTE(Mardikes @ Apr 28 2006, 09:26 AM) [snapback]246672[/snapback]</div>

Quote:

It seems to me that it would be easy to basically reprogram the computers to reduce that maximum acceleration.
[/b]

If it were that simple and had only the effects that you've listed, why wouldn't Toyota already have done this during its years of research into hybrid propulsion?

Or, to put it another way, maybe Toyota has already done this, and the hybrid drive's current settings already reflect that balancing act.

Mardikes · 04-28-2006, 12:52 PM

<div class='quotetop'>QUOTE(Frank Hudon @ Apr 28 2006, 09:30 AM) [snapback]246674[/snapback]</div>

Quote:

cheaper and easier and no potential problems is to reprogram your foot.
[/b]

Believe me, that is really hard for the HiHy. It just does not take much pressure to start it racing and I have pretty good control of my right foot from drumming. Besides, I cannot control other members of the family when they drive the vehicle.

<div class='quotetop'>QUOTE(highroute @ Apr 28 2006, 09:44 AM) [snapback]246683[/snapback]</div>

Quote:

If it were that simple and had only the effects that you've listed, why wouldn't Toyota already have done this during its years of research into hybrid propulsion?

Or, to put it another way, maybe Toyota has already done this, and the hybrid drive's current settings already reflect that balancing act.
[/b]

Yes, they have already done this to a certain extent. At least in having maximum power without destroying the transmission. My thought is to back off a bit more.

I can see no technological reason they could not reprogram the Prius to do 0 to 60 in 14 seconds. What effect on MPG would it have if they did so?

George

ScottY · 04-28-2006, 12:59 PM

<div class='quotetop'>QUOTE(Mardikes @ Apr 28 2006, 12:52 PM) [snapback]246685[/snapback]</div>

Quote:

...
I can see no technological reason they could not reprogram the Prius to do 0 to 60 in 14 seconds. What effect on MPG would it have if they did so?

George
[/b]

You can go from 0 to 60 in 14 sec, just don't step on gas that much. :P

hobbit · 04-28-2006, 01:13 PM

Given that some people do 40 mpg and some push 70 mpg in identical
cars, there's a lot to be said for driving style. Up at that level
some very subtle things can have a pretty radical effect on fuel
usage. [A bird poops on the hood, and there goes your average!]
.
_H*

PriusDad · 04-28-2006, 05:56 PM

<div class='quotetop'>QUOTE(Mardikes @ Apr 28 2006, 09:26 AM) [snapback]246672[/snapback]</div>

Quote:

After owning a 2001 Prius and a 2002 Prius, we sold both and bought a 2006 Highlander Hybrid and have on order a 2006 Prius.

I find that in driving the HiHy, that one really has to watch the acceleration. The car has incredible power, but more than we want or need. The single most important factor for me for MPG is how heavy my foot is.

These vehicles are bascially computer driven. When I put my foot on the gas, it is not mechanically increasing the gas, but instead inputting information to the computer to increase speed.

The computer already limits the maximum speed one can drive.

It also limits the maximum torque of the combined power to avoid destruction of the transmission, which basically is a limitation on maximum acceleration.

It seems to me that it would be easy to basically reprogram the computers to reduce that maximum acceleration.

One would need to limit the maximum acceleration from both the engine and the motor, otherwise the computer would put excessive strain on the battery and motor system instead of the engine.

It seems to me that this would possibly increase MPG. I am sure it would for the HiHy, probably less so for the Prius.

In essence, similar to computer that can be modified to make them faster -- overclocking-- we would be modifying the hybrid to make them slower, at least as to acceleration -- underclocking.

Now Toyota might not like to do this. For example, if someone does not know the vehicle is underclocked, then the person driving may not be impressed with the potential power of the vehicle. To solve this one might have a warning on the dashboard stating that the vehicle has been underclocked by the owner.

If this is possible, it might make sense for the Sierra Club, National Resources Defense Council and other green groups to lobby Toyota to allow these modifications.

Thoughts?

George

P.S. I would prefer to focus this posting on the technological issue of whether the reprograming could be done, not alternative work arounds, like being more careful at driving (I cannot control all of the drivers in our family) or using cruise control (not realistic in the city).
[/b]

I swear I saw this somewhere, but can't remember where... I thought the Toyota hybrids (because of the electronic accelerator) had a sensitivity adjust. You may want to ask the service department at your Toyota dealer if such an adjustment exists, and if they can make it for you or tell you how to do it.

Peter.

tomdeimos · 04-28-2006, 09:58 PM

Just fix the accelerator so you can only push it down half way.

V8Cobrakid · 04-28-2006, 10:11 PM

the RX400h and the HyHi are running the same specs right? If so... just get up to speed a little quick. not too quickly. then cruise. i know the 400h will cruise a lot longer than a normal car.. so get up to speed an cost behind other cars. It's not too hard to get over 30mpg in these vehicles... if you don't want o have fun punching it.

04-28-2006, 12:26 PM	#1
Mardikes Join Date: Mar 2006 Posts: 50 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	After owning a 2001 Prius and a 2002 Prius, we sold both and bought a 2006 Highlander Hybrid and have on order a 2006 Prius. I find that in driving the HiHy, that one really has to watch the acceleration. The car has incredible power, but more than we want or need. The single most important factor for me for MPG is how heavy my foot is. These vehicles are bascially computer driven. When I put my foot on the gas, it is not mechanically increasing the gas, but instead inputting information to the computer to increase speed. The computer already limits the maximum speed one can drive. It also limits the maximum torque of the combined power to avoid destruction of the transmission, which basically is a limitation on maximum acceleration. It seems to me that it would be easy to basically reprogram the computers to reduce that maximum acceleration. One would need to limit the maximum acceleration from both the engine and the motor, otherwise the computer would put excessive strain on the battery and motor system instead of the engine. It seems to me that this would possibly increase MPG. I am sure it would for the HiHy, probably less so for the Prius. In essence, similar to computer that can be modified to make them faster -- overclocking-- we would be modifying the hybrid to make them slower, at least as to acceleration -- underclocking. Now Toyota might not like to do this. For example, if someone does not know the vehicle is underclocked, then the person driving may not be impressed with the potential power of the vehicle. To solve this one might have a warning on the dashboard stating that the vehicle has been underclocked by the owner. If this is possible, it might make sense for the Sierra Club, National Resources Defense Council and other green groups to lobby Toyota to allow these modifications. Thoughts? George P.S. I would prefer to focus this posting on the technological issue of whether the reprograming could be done, not alternative work arounds, like being more careful at driving (I cannot control all of the drivers in our family) or using cruise control (not realistic in the city). __________________ George 2006 Prius 2006 HiHy Formerly 2001 & 2002 Prius

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04-28-2006, 12:30 PM	#2
Frank Hudon Senior Member Join Date: Jan 2004 Posts: 4,144 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	cheaper and easier and no potential problems is to reprogram your foot.

04-28-2006, 12:43 PM	#3
mikepaul Senior Member Join Date: Dec 2003 Location: Columbia, SC Posts: 1,676 My Car: 2004 Prius Package: #9 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	I use the cruise control as often as possible, highway or not. I rarely see where my foot does better. Maybe there are horror stories of old-school cruise sticking and causing accidents, but with throttle-by-wire that hardly seems an issue. I say stick with as much computer control as you can, and hope for improvement...

04-28-2006, 01:13 PM	#7
hobbit Senior Member Join Date: Mar 2005 Location: Bahstahn Posts: 2,989 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Given that some people do 40 mpg and some push 70 mpg in identical cars, there's a lot to be said for driving style. Up at that level some very subtle things can have a pretty radical effect on fuel usage. [A bird poops on the hood, and there goes your average!] . _H*

04-28-2006, 09:58 PM	#9
tomdeimos Join Date: Feb 2004 Location: Lexington, MA Posts: 995 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Just fix the accelerator so you can only push it down half way.

04-28-2006, 10:11 PM	#10
V8Cobrakid some guy... Join Date: Jun 2004 Location: San Jose, CA Posts: 2,566 My Car: 2004 Prius Package: #9 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 5	the RX400h and the HyHi are running the same specs right? If so... just get up to speed a little quick. not too quickly. then cruise. i know the 400h will cruise a lot longer than a normal car.. so get up to speed an cost behind other cars. It's not too hard to get over 30mpg in these vehicles... if you don't want o have fun punching it.