Comments on: How Should the Chevy Volt’s mpg be Calculated?

By: bluemonkey

bluemonkey — Mon, 17 Aug 2009 00:13:29 +0000

The electric car is very easy to built, and very effective.
In 1899, a Belgian built electric racing car called “La Jamais Contente” set a world record for land speed – 68 mph – designed by Camille Jénatzy.
The battery pack is very short-lived, and very, very expensive.
This is the reason why “the piston cars”, are around for more than 100 years.
Their efficiency is 25% only, and still is more effective than an Electric Car.
The Battery pack is the Achilles’ heel of an Electric car.

By: Randy Hudson

Randy Hudson — Sat, 15 Aug 2009 17:06:59 +0000

One other consideration, not directly related to MPG: What will the highway taxes be? A substantial portion of the cost of a gallon of gasoline is the state and federal excise taxes that fund construction and maintenance of our roads. Either the very idea of funding that by excise taxes will need to be dropped, or excise taxes will be assessed on the electricity used for driving on roads.

For most passenger vehicles, gasoline taxes amount to between 1 and 2 cents per mile driven. If the Volt users actually average 230 MPG, then they’ll be paying around a tenth of that, for a car whose curb weight (including the weight of the batteries) is similar, and so cannot be said to impose less wear and tear on the roads they use. Soon, therefore, governments will move to add roughly-equivalent excise taxes to the use of electricity for transport, as they moved to tax diesel fuel in the 1970s and transportation propane in this millennium.

By: bill

bill — Wed, 12 Aug 2009 01:37:14 +0000

GM isnt going to want the cost per mile published. It turns out that those 16kwh used to drive the vehicle 40 miles will cost upwards of $5 worth of electricity to recharge. Thats based on 20kwh at 25 cents per kwh. You cant put 16kwh into the batteries with 16kwh… it takes more. It might be only half that cost in the south where electricity might be had for 12cents per kwh, but not in the west and northeast. Another thing is the cost of the vehicle itself. You can figure on a $20,000 depreciation over a few years. That might be 50cents a mile. So it looks to me like a $40,000 vehicle that really gets 25mpg give or take. Not too sporty.

By: Aaron

Aaron — Sat, 13 Sep 2008 03:53:51 +0000

The answer to the GM vs. EPA issue is very simple.

EPA needs to update their standards to accommodate new technology. Most simply and most universally, they should use the Joule to measure how much energy is being consumed to move your vehicle. Gasoline and all liquid fuels have a defined energy density, so this measurement is very simple to apply to those. Likewise, batteries have a specific number of Joules stored so this standard can be easily applied to them as well.

Gasoline has an energy density of 34.6 MJ/L (per wikipedia) This means a car that gets 40MPG gets .3054 Miles per MegaJoule

I envision a new sticker readout that says something like:

Miles per MegaJoule City (10 mile test): .3280
Miles per MegaJoule Highway (30 mile test): .3366
Miles per MegaJoule Highway (full to empty): .3235

The sticker would have to specify the ratio of Joules drawn from each source in the vehicle for each test, but I am leaving that out because I can’t format anything in this post. It could even be presented as a pie chart for the consumer.

This would give the EPA the most simple and universal standard to protect the environment.

By: dennis

dennis — Fri, 12 Sep 2008 18:17:48 +0000

The MPG should be calculated by the total miles driven on a full tank of gas divided by the number of gallons in the tank.
KISS

(Total miles driven on 1 tank)/(gallons in the tank)

Plus stick the number of miles you can drive on a single charge somewhere