More on the Volt

Chevy Volt.  The burning question in many people’s minds is this:  How much electricity does that electric portion of the trip use?  GM answers that question (sort of) in a new press release:

“Applying EPA’s methodology, GM expects the Volt to consume as little as 25 kilowatt hours per 100 miles in city driving.”

That’s a number we can work with.  25 Kwh per 100 miles means the Volt will consumer 10 Kwh during its 40 mile electric-only portion of a journey.  That’s 15 pounds of CO2– 20 if your utility uses exclusively coal-fired generation. Â To put it in cruder terms, the Volt takes 0.0975 pounds of coal (20 pounds of CO2 / 205 pounds everage CO2 per pound of coal) to travel those 40 miles, so it will go 410 miles on the electricity generated by a pound of coal.

Keep in mind, that most trips people make are short ones. DOT puts Americans’ mean trip length at 10 miles, where Volt excels. Even on a 40-mile trip, Volt uses an estimated 10 Kwh and no gas. That’s 15 pounds CO2 emissions compared to Prius’s 19 pounds. Even if you drive 100 miles at a time, your net fuel consumption would be (40*0) + (60*1/62.5)= 1.2 gallons + 15 Kwh. That still compares favorably with 1.9 gallons of gasoline in the 2010 Prius. On CO2 emissions, there’s little difference, though: Volt would emit about 39 pounds of CO2 for the trip compared to Prius’s 38 pounds.

As the trip lengthens, the difference in fuel consumption diminishes also. The 2010 Prius claims 53 mpg, while the Volt gets 50 mpg beyond its 40 mile electric range– a difference that’s statistically insignifiant.  (You’d save 1.2 gallons over 1,000 miles in the Prius compared with Volt’s 20 gallons, assuming you drove like EPA does.)

The high price and high minimum operating temperature will keep a lot of us from buying the Volt (how do you get to work when the temp is -30?), but it’s still a step in the right direction.  Especially if (as the GM press release indicates) Volt’s generator is flex-fueled, meaning it can run on fuels other than gasoline.

About that supposed 230 mpg for the Chevy Volt

It’s only true is the car goes exactly 51.1 miles. Environmental Economics crunched the numbers. NPR agrees.

For a trip of 50 miles, the Volt gets 250 miles per gallon. But, for a trip of 200 miles, the Volt gets 62.5 mpg. Based on the EPA decision to rate the Volt at 230 mpg, they are assuming a trip of 51.11 miles.

Left unanswered: what is the EPA mppc (miles per pound of coal) for the Volt when running off the electric engine?

GM made a mistake by touting 230 mpg, a number they devised. Even EPA hasn’t agreed with it. I hope the Volt is a game changer, but GM has a long and tired history of doing innovative things on one hand, then screwing them up on the other. Plus, with a price starting at $40,000 and needing a minimum temperature between 32°F to 50°F to run on the battery alone,I wonder just how practical it is and how many will sell.

Chevy Volt’s 230 mpg in perspective

Broken Sword photo
Broken Sword photo

GM, using EPA standards, predicts that the Chevy Volt will get 230 mpg— an astounding figure for a big-six vehicle.  It’s commonly compared with Toyota Prius’s 48 mpg.  But that’s only because several higher mileage cars, like the 70 mpg VW Polo, aren’t sold in the U.S.

The mpg figure makes the Volt look better than it is, but it’s a huge step forward.  Here are some comparisons:

Vehicle MPG Gals/100 mi Annual CO2 (Lbs)
2008 Ford F-150 2WD 18 5.6 13,320
2009 Honda Civic (stick) 34 2.9 7,059
2010 Toyota Prius 53 1.9 4,528
2010 Chevy Volt (est) 230 0.43 2,868*

* The Volt will contribute 1,043 pounds of CO2 per year based on gasoline consumed in an average driver’s annual 12,000 miles.  That’s pretty amazing.  But keep in mind that the Volt uses electricity, too– of which half comes from coal, and another quarter from other fossil fuel sources.  GM hasn’t released electricity consumption data yet, but it does say that the Volt will cost 40 cents per day to charge.  At an average price of 12 cents per Kwh, that gives a rough estimate of 3.33 Kwh per day, or 1,217 per year, equating to another 1,825 pounds of CO2 emitted.

Volt’s emissions are still 1/3 less than a Prius, 60% less than the latest Honda Civic, and 78% less than a Ford F-150.  Bravo GM!