How the Chevy Volt Will Transform Fuel Economy

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First of all - you are quite right - I decided to let the Kilowatts vs. Kilowatt-Hour thing slip since it's such a common error and people would know what he meant. I didn't want to sound pedantic I suppose. I've grown mellow in my old age I suppose. :o)
As far as your point about the acceleration - what you describe would virtually never happen. The car never depletes the battery fully - the battery is charged in a sweet spot range between 30%-85% state of charge (the battery itself is about 16KwH at the beginning of its life; the "available" capacity at the battery is about 8.8KwH per GM). This is done because it reduces strain on the battery and greatly extends its life (Lithium Ion batteries are unlikely most other battery technologies: it does not like to be deep cycled). Once the battery reaches below a certain charge threshold the generator kicks in to recharge the battery and keep its state of charge above a minimum state. The car would still have plenty of reserve energy for acceleration which is expected to be in the 8 second range (yes the car is heavy - but you have to remember that the energy provided from the electric motor is extremely torquey and, with no transmission, there are virtually no drivetrain losses or power losses related to shifting from the 160HP motor).
The only instance where this could possibly happen would be driving up a steep hill for a long, long period of time (Pike's Peak type driving) at a high speed (60-70MPH+). Given that there are no infinitely long hills that people travel at high speeds up this should not be a problem.
As far as the "non-plug in" MPG - for city driving its expected to be Prius-like at about 50 mpg per GM. I believe the draft standards require that the car also run through the standard EPA course on gas to determine unplugged MPG so we should see once the car has been released. At the very least review sites will be happy to educate us on the electricity free MPG of the car - likely long before it even goes on sale to the public.

Chris of GA 6:07PM August 11, 2009

It's a niggle, but electrical energy is measured in kilowatt-hours, not killowatts. Using the unit killowatts to describe energy is like using the unit miles-per-hour to describe distance.
IMO, the numbers like this used by various hybrid manufacturers are useless and border on being fraudulent. By these standards, an all-electric vehicle such as the Tesla Roadstser, or even a bicycle for that matter, gets infinite miles per gallon, which is an absurd and useless metric.
What I'd like to know, and GM may never tell me, is how many miles per gallon I will get if I never plug the car in. That will tell me something about the car's efficiency in a way that some EPA combined, boiled down, oversimplified number won't. Bogus inflated numbers like certainly 230 mpg won't.
To Chris-from-GA's point about performance: maintaining steady state speed requires very little power, so 90 mph sustained is not impressive. What is more important is the 0-60 time for a car with a depleted battery and a 53 KHW motor (~71 horsepower). For such a heavy car, in the worst case where the battery is truly depleted, the 0-60 time is likely around 30 seconds. Not a frequent or likely occurrence, but possible.

Dan of MA 5:51PM August 11, 2009

Maybe Rick will do some research on his next column. Chris nicely pointed outed two big gaffes in this piece of journalism

bryan of PA 5:38PM August 11, 2009

You stated that the EPA/US Government would not endorse these figures. This is incorrect: the MPG is calculated from the official draft standards for the rating of plugin hybrids by the EPA. These standards are more or less already set in stone and are unlikely to change. You questioned how else the efficiency would be measured - and it is measured in KwH/100 miles (much like the European L/100km measures you discussed). In this case it's 25KwH/100 miles or so.
Also - you stated that once the battery has drained the driving experience will be poor. This is incorrect; the gas engine never runs the wheels - only the electric motor does. The gas engine merely charges the batteries and, as a 53KW generator, that is more than enough for average load driving at 90MPH. Acceleration would remain constant.

Chris of GA 5:29PM August 11, 2009