More on the GM and EPA 230-mpg controversy (updated)

Nothing to see here. Move along, move along! Just ignore that man behind the curtain. Obama-owned Government Motors (GM) can just talk to the government regulator (EPA) to use whatever MPG number they want. Don't question the authorities! This is an easy way to crowd out competition from this newly founded gov't monopoly. After all, it's for a good cause; the American citizens need their money back from GM. El Duce, Benito Mussolini, would be proud.....

A single number will never reflect the ecconomy of a multi-fuel vehicle. Trying to make comparisions to equate kWhr to gallons is futile, becuse the consumer cares about cost, and the cost of these commodities varies widely. Even in one locality there are huge variations. For example, my utility has tiered electric rates (as do most in urban centers), so while my first few kWhr cost about 12 cents, the ones that would recharge a car would be added on top of my present useage, and be billed at 25 to 31 cents per kWhr. If GM really wanted to give consumers an idea of what to expect, they would put a little calculator app on their website. You could enter the following: YOUR cost of gas per gallon. YOUR cost of electricity per kWhr. Miles to be driven. Type of trip (local, highway, mixed). Click OK, and the estimated energy cost in dollars for the trip is calculated. You could easily compare this with your current costs of your gas-only car. GM will probably never do this, because it would cause the hype of the Volt to evaporate. They have already admitted that the 230 MPG figure does not include the cost of the electricity used. Yet, using reasonable engineering calculations (see note below), at my tiered electric rate, I do not see electricity as being any less costly than the gasoline it replaces. Consequently, operating the Volt would actually cost about the same as any other hybrid claiming an ~40 MPG gas-only fuel economy. NOTE: Many published attempts to compare gasoline and elecricity are flawed, because they base computations on the theoretical chemical energy in a gallon of gasoline vs a kWhr of electricity (3600 kJ). However, it is necessary to account for the low efficiency of even the best internal combustion engines and losses in the hybrid power train, which seems to be rarely done correctly. A more direct and accurate method is to determine the kWhr used in recharging (somewhat more than the battery capacity, as charging is not lossless) and divide by the claimed "electric only" distance. This gives you kWhr/mile, from which you can compute the cost per mile.

A Joule is a watt-second is a Calorie, so being told a car needs 12 kilowatt-hours to go forty miles is as good a metric as any. Even then, however, there are a couple of problems: regenerative braking makes comparisons 'unfair', and building solar cells into the roof would make metering use a bit more involved. And of course, recharging at home means you don't drive to a gas station. Consumers are now having to think about their energy footprint, and milage alone is pretty useless. One has to consider the cost of replacing a car, buying food for home cooking vs eating out, and buying goods made out of plastic in comparison to goods made out of metal or glass. This is further complicated when apparently minor changes or improvements in technology affect costs on a large scale. It might be better for the EPA to publish the 'footprint' equivalent, which shows how much carbon is emitted when recharging a hybrid from a coal plant, a natural gas plant, wind turbines, or hydroelectric. The car dealer could display a poster showing the mix of generation options in use in that area. This is all fine print. Most people wouldn't pay any attention.