[ausev] GM to build plug in hybrid

[Marc Kohler]

Good point Danny,
It was one of the main topics that was discussed at the DOE PHEV conference in May.  

A vehicle can be optimized for either highway or city use, regardless if it is a PHEV or not.  You can have charge depleting strategies, where the vehicle uses it's electrical assist (EV mode or with gas engine on) feature as much as possible from the moment you start your first mile.  This method would give you the greatest (mpg) for people who use the car less than 50 miles per day.  Another option would be to only use the electric assist under a certain speed (think inner city deliveries then driving to the next city on the highway).  This strategy might give a delivery van, like the Sprinter, a better overall fuel economy when you dissect the drivetrains' operation and let each do what they do best (elec motor in the city, diesel on the highway).  The third option could be only to use the electric assist when on the hwy, as for some drivers, that's where they spend a majority of their time, so use the extra electrical assist where it's used most, not just a few starts of a (greater than) 50 mile journey.  

One of the main requests from industry was for the DOE to create some standardization.  A part of that would be what the definition of a PHEV is.  
For example: Any vehicle that uses electricity from the grid and displaces fuel, 

rather than "a vehicle that has a 20 mile range using EV mode only".  Even though this is very attractive, the general market assumes that the car will perform the same (acceleration, speed, etc) in those first 20 miles as it does in a gas car.  Very few PHEVs behave like that as the electric motor is too small.  Using the first definition allows the manufacturer to choose what is best for the vehicle they can build and for what target market they hope to attack.  This would mean a PHEV could be a van with 20 miles of EV mode range or it could be a Honda Insight-like vehicle with 30 minutes of electric assist while cruising on the highway.  Each may displace the same amount of fuel in the end.

And, just like the UDDS urban and hwy driving cycles that are used today to show EPA fuel economy numbers, so too must a profile be selected for allowing different PHEVs, with their different strategies, to be compared evenly.

A representative from Ford suggested the following:
1) Define a short driving cycle (2-5 miles)
2) Drive in depletion mode till depleted, yielding these two numbers.  Range(d), and mpg(d)
3) Drive in sustaining mode (like HEVs do today), which will give you mpg(s)
4) Determine an Electric Equivalent Range = Range(d)(1- (mpg(s)/mpg(d)))

Using this method, a PHEV would have an Electric Equivalent Range (EER), instead of what is now thought of as PHEV-20 (20 miles of EV use), PHEV-50, etc.

One other option to the EER would be to state something as Gallons of Fuel Displaced, but that would be much harder to quantify because it would need something standard to compare to (i.e. a standard car, or a standard HEV?).

Marc Kohler
  ----- Original Message ----- 
  From: Daniel J. Stewart 
  To: AustinEV announcements list 
  Sent: Tuesday, July 04, 2006 1:20 PM
  Subject: Re: [ausev] GM to build plug in hybrid



  You wonder how they decide what "miles per gallon" to say for plug-in hybrids.  This article says 60 (which sounds pretty lame to an Insight driver like me) but if it truly has an all-electric mode, then someone with small commuting needs could get a whole lot more, while someone that never gets in their car without driving 300 miles (which the plug-in opponents seem to believe is just about everyone) would average less.



       -------Original Message-------
        From: Mark Farver 
        Subject: [ausev] GM to build plug in hybrid
        Sent: 03 Jul '06 17:13

        Bloomburg reports of a crash effort at GM to build a prototype plug in 
        hybrid by Jan 2007 with production starting near the end of 2007.

        http://www.iht.com/articles/2006/06/23/business/plugin.php

        It will be interesting to see if they succeed or if this will be a half 
        try like the "slap on a bigger starter" mild hybrid Silverado. On the 
        plus side this is likely to spur Toyota to release a plug in, and with 
        Toyota's leg up in technology they should be able to do it much sooner.

        Mark
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