"Coast" Button

You can't really map the accelerator to percentages
of travel in which running conditions are
dictated in any particular fashion. The pedal
is a request for a certain amount of output torque,
i.e. acceleration and a steady-state RPM to maintain
a certain speed. Whether the engine comes on or not depends on a
balance between that request and the battery SOC. If the SOC
is low, there's a greater *probability* that the ICE will
come on to both aid acceleration and push a little
more charge into the battery and seek back to that
nominal 60% level. It's a smooth continuum.
.
If you think about it, the way the system currently
works encourages pulse-n-glide in a way -- run the ICE to
accelerate, and use some mix of ICE and electric to
maintain. Unfortunately the brain sometimes gets it wrong
at light demands, letting the engine start but then "loaf"
without producing much power. You can widen this hysteresis by
judicious use of your foot.
.
I finally put together a single picture that shows
why pulse-n-glide works to improve mileage.
The idea is to keep the engine high on the efficiency curve
when it's running, or shut down completely, but
never fall off the left side:
http://techno-fandom.org/~hobbit/cars/prius-curves.gif
.
A recent discussion over in the prius_technical_stuff
yahoogroup [highly recommended] brought to light that
no-arrows glide mode and N are *slightly* different. Glide appears
to draw a few hundred watts from the battery, whereas
N cuts all motor current flow completely. Probably impossible
to butt-feel any difference.
.
_H*

 

I understand why regenerative braking kicks in when the accelerator not depressed, since it mimicks the feel of existing cars. It may be nice to have an option to turn this off, but then there is always the issue of if someone who is use to driving a normal car is borrowing a Prius or something.

There is the inconsistency that the car freewheels once the battery is topped off, so I would say for consistency engine braking should occur at this point , or regenerative braking/engine braking when accelerator not depressed should be disabled period.

As for a "coast" button, I think to follow the regular car analogy, a clutch would be the most familiar. It would be optional whether you use it or not, and of course be sort of unusual to have an clutch in a "AT" vehicle. On the other the "AT" isn't like a traditional "AT", so maybe the two inconsistencies are at least consistently inconsistent.

 

How bout an MT with automatic clutch mode? MTs freewheel. It could be a setting that has to be engaged at each trip (like many other things in the car) if safety is a concern.
A programmable drive mode, that lets you pulse drive within 10 miles of a set point? I tried the pulse and glide, I can't seem to get it to work and get any more efficiency than standard CC. At least not at speeds greater than 45 MPH. I certainly can see how it would work below that, as the car tends to favor EV at speeds under 40.

 

<div class='quotetop'>QUOTE(DanMan32\";p=\"116803)</div>

I think pulse glide is helping me at speed. But based on what I read about the Marathon the key is a road that goes up and down. On level highway might as well use cruise control.

Over on Yahoo there is a pretty good explanation. Forget where.
But it covers pulse glide and pulse to battery power.

Anyway the gist was pulse glide can only help when engine is really lightly loaded.
Then you are better having it just off. This could be caused by slow speeds. But also by higher speed but going down hill, or by a strong tailwind.

And free wheeling should be required on all cars. It was great back when I drove Saabs.
Takes less time to adjust to it than different types of brake power assists. We never turned it off except going down mountains to keep brakes from overheating. B mode already covers that if D did the freewheeling.

 

<div class='quotetop'>QUOTE(DanMan32\";p=\"116803)</div>

MT? I don't see how it could be MT since there are no gears to shift between and that would require adding some sort gearing or programming that mimics gearing, which would probably be less efficient than a CVT.

We might be describing the same thing. If you have an AT with a clutch, if you don't use the clutch at all it behaves with engine braking/regenerative braking and you don't need a setting. You simply don't use the clutch.