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Quote from: Living With the Chevy Volt: the First 1300 Miles ( http://gm-volt.com/2010/11/29/living-with-the-chevy-volt-the-first-1300-miles/ )
Efficiency
…I primarily use the sport mode which has a more aggressive pedal map, but is noted by GM not to reduce efficiency over the normal mode.
Someone help me with this? This does not seem to pass my smell test. Seems like the driver in this mode would use more resources … wouldn’t the battery drain slightly quicker in steep acceleration vs modest (no correlation to jackrabbit gas car starts?). Also it seems sport mode would mentally cause the driver to drive more aggressive (green ball turning yellow). (aside: I understand Sports mode also changes steering).

Also then why would they provide normal vs sport if sport was just as economical? Just for the drivers “experience” and “feedback” (ie. some want a sportier car vs econ “feel” car).
 

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Very good point Scottf! In my test drive I thought I was seeing the green ball turn yellow more in sport mode than in normal mode, which is what you would expect, and which would indicate sport mode is less efficient because you will accelerate faster with the same push of the accelerator pedal.

Perhaps GM's point is that you "could" really feather the accelerator pedal in sport mode, in effect mimicking normal mode, and you "could" always floor it in normal mode, which shows there's nothing inherently less efficient about sport mode. But in real world use, sport mode must be less efficient than normal mode, assuming the same push of the accelerator pedal in both modes.

Also they might be trying to make the point that flooring it in either mode produces the exact same response. Flooring it in sport mode does not accelerate any faster than flooring it in normal mode.
 

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I asked Lyle that same question the day his great article came out and he said it is true and that only the pedal map is different. Of course I have no idea what that means. Can someone explain that because when I drove the volt the engineer specifically told me you would get less ev range in sport mode. Maybe when Lyle does his commute in one mode versus the other he arrives at work with the same EV range left.
 

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The pedal map means how far do you have to push the pedal to get a response? The pedal is more responsive in Sport mode. In normal mode you would have to push the pedal, say 50% of the way down, to get the same response as you would see in Sport mode by pushing it 25% of the way down. That's not exact, just an example.
 

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The pedal map means how far do you have to push the pedal to get a response? The pedal is more responsive in Sport mode. In normal mode you would have to push the pedal, say 50% of the way down, to get the same response as you would see in Sport mode by pushing it 25% of the way down. That's not exact, just an example.
Sort of. The pedal mechanism itself has an analog input device (called an APP- Accelerator Pedal Position sensor) that inversely varies a couple of voltages. So as the pedal is applied by the driver the voltages equate to a % of accelerator pedal travel. Then there is a throttle "map" , part of the engine control module calibration that equates the % of pedal travel to a % of requested/delivered torque. The Sport Mode on the Volt alters these percentages so that it is more agressive i.e. the same amount of pedal creates more requested torque delivery than in normal mode. This is mot apparent at lower throttle openings and gives the Volt more "jump" however as the % of travel approaches maximum the differences in the map are gradually equalized so that at WOT the maximum delivered torque is essentially equal.

As Lyle has noted if you are holding the throttle at a steady point and switch over to Sport Mode, the car willimmediately respond with more acceleration, as the Sport map would be requesting more torque at any given low-intermediate pedal position

HTH
WopOnTour
 

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Depends on how you drive. Assuming you press the pedal down the exact same amount under both modes, you will accelerate faster in sport mode and thus get less EV range in sport mode. But if you really feather it in sport mode you could get the same EV range as a heavier foot in normal mode. For best EV range, use normal mode and feather your acceleration.
 

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If so, why would they offer a normal mode?
The zero-RPM torque performance of the electric motor would startle the average Joe driver. They basically made the beginning travel of the accelerator "mushy" to make it feel more like a regular car. Thankfully they gave us the option of getting the real thing via "Sport" mode. Please don't complain :)
 

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Discussion Starter · #9 ·
The zero-RPM torque performance of the electric motor would startle the average Joe driver. They basically made the beginning travel of the accelerator "mushy" to make it feel more like a regular car.
That makes common sense to me. Sports mode is a good feature to show your friends <grin>.
 

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Throtal response Norm vs Sport

The common term used to describe gas pedal feel is Tip In response. And it is true that with an electric traction motor this could be really wild ride if it was done in purely linear manner. What is interesting is that you could put all kinds of Tip In feel. You could even have a configuration in the cars software that could be set from 0 to 10 with the 0 being the lightest feel (mushy) to 10 rip your head off and suck the wind from you response. That could be fun.

P
 

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I always use sport mode and get the same EV miles as my wife who uses normal mode. I just wish I could change the default setting when starting to sport to avoid double clcking drive mode each time.
 

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I don't understand why quick acceleration uses more energy. As a physicist I know that it takes the same amount of energy to accelerate something quickly as it does slowly. If the final velocity is the same, the total change in kinetic energy will be the same. So why does it take more energy to accelerate the Volt faster?

I can see with an ICE, where flooring the pedal injects extra fuel into the cylinder. Is the electric motor also less efficient for some reason when it puts out more torque? That's the only explanation I can think of, but perhaps I'm missing something.
 

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I don't understand why quick acceleration uses more energy. As a physicist I know that it takes the same amount of energy to accelerate something quickly as it does slowly. If the final velocity is the same, the total change in kinetic energy will be the same. So why does it take more energy to accelerate the Volt faster?

I can see with an ICE, where flooring the pedal injects extra fuel into the cylinder. Is the electric motor also less efficient for some reason when it puts out more torque? That's the only explanation I can think of, but perhaps I'm missing something.


Voltage is constant so increasing power need to accelerate aggressively requires increasing current. So since the power loss due to wire resistance in the windings increases as the square of the current the motor's losses are a factor of I^2 R. More acceleration requires more current increasing loss quadratically. Not as bad as an ICE loss but still noticeable.
 

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Why can't Sport mode be left on without it getting reset everytime you turn off the car? For those of us who are not tree huggers, we bought Volt over Prius for performance, not economy.

(yes and maybe the Green sticker for the CA HOV lane).
 

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Why can't Sport mode be left on without it getting reset everytime you turn off the car? For those of us who are not tree huggers, we bought Volt over Prius for performance, not economy. (yes and maybe the Green sticker for the CA HOV lane).
This has been talked about for a couple years. Changes the responsiveness of the pedal. So if you significant other or kid are doing the car driveway shuffle or pulling out the garage and it was "jumpy" as in sports mode responsive it could cause a problem as you could imagine.
 
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