Saturday, August 15, 2009

Your mileage may vary

You must have seen the ads by now; they're everywhere- Chevy Volt 230 , with the zero being an electrical socket photoshopped into a smiley-face. (which drives a lot of parents up a wall) It drives me up a wall, too, even though I don't have any children... because it's bullshit.

It cannot be done in a street legal car using an internal combustion engine. Period. Yes, tissue-fragile deathtrap vehicles just large enough for a human body have gotten over a thousand miles per gallon on a perfectly level, smooth test track- but the laws of physics won't permit an automobile that meets all US regulations to reach triple-digit mileage. (I give a short explanation here ) 230 MPG? That would mean you could drive from Miami to Seattle on one 12-gallon tank, and have enough left over to drive around Seattle to the shops and dinner! If you believe that, I have a few other bargains for you as well...

But you don't have to take my word for it- you can figure it out from their own published information. The Chevrolet main site doesn't have any specs, but they have a facebook page to answer questions- just make sure your browser is gyro-stabilized to handle the spin. The battery lasts for 40 miles, after which the gasoline engine/generator supplies the electricity, for a total of 300 miles per tankfull. 300, not 2,300. Which, according to this US News & World Report article, translates to about 35 MPG. But wait, Chevy says, there is a formula to draw an energy equivalency to mileage here: "The EPA's tentative EREV testing process won't actually measure gasoline usage. Instead, it rates vehicles in kilowatt hours per 100 miles, then converts that measurement to miles per gallon. Effectively, the testing procedure doesn't give an mpg rating. It merely shows that a vehicle will use energy that equates to a certain mpg rating.
To illustrate this point, Nissan quickly followed GM's announcement with its own, claiming the upcoming 2010 Nissan Leaf electric car will earn a 367 mpg EPA rating. The rules, it seems, can generate a miles-per-gallon rating for a car that doesn't even use gasoline."

Let me propose another formula: compare costs; since one must buy both the kilowatt/hours and the gallons, that should yield an equivalent. Chevy initially said it would cost $0.40 to charge the Volt- at least until some reporter asked where one could buy 16 KW for $0.40. Now they say between $0.75 and $2.50, depending upon where you live. I live in Indianapolis, where we pay $0.08/KW; that's $1.28 to charge the Volt. That would buy just about a half gallon of gas at the national average of $2.44 the EPA uses for mileage calculations. For a distance of 40 miles, that's equivalent to 80 MPG. That's damn good, but it's NOT 230MPG.

Why the extravagant claim when the truth- 80MPG- is impressive enough as is? Maybe they knew that with a $40,000 price tag they needed to make a "not price, but value" argument. If so, it backfired; had they made a believable claim, I'd have looked no farther. As it is, I decided to run the numbers. The Volt has a maximum lifespan of 15 years- that's how long the $10,000 battery lasts. (At best; some experts say it's more like 10 years) Let's take the best possible scenario: I never drive more than 40 miles in a day, and therefore never burn a drop of gas. $1.28/day times 365 days is $467.20/year. 15 years at $467.20/year is $7,000; plus the $40,000 purchase price is $47,000 for the 17 year lifespan. If I lived where the cost of the daily charge was $2.50, it would be $13,688 for electricity, $53,688 total. How does that compare to a normal, inefficient, old-technology car?

If you go to you'll find a lot of cars getting 30MPG. 40 miles per day at 30 miles per gallon is 486.67 gallons a year; at the $2.44 average price of a gallon, that's $1,187 per year; times 15 years is $17,812 for gasoline. That's more than double what you'd pay for the electricity to run the Volt at the cheapest KW price; it's even a third higher than the highest KW price. But look at purchase price- a comparably equipped four door sedan runs between $13,000 and $18,000, not $40,000. Let's say $16,000- there are quite a few at that price or less. That makes the total of purchase price and gasoline $33,812... between $13,000 and $19,000 cheaper than the Volt!

But wait- what if the price of gas goes up? Ok... in the example above, at 30MPG, same miles driven for 15 years, you've bought 7,300 gallons of gas. Say it goes up to $4.00 per gallon- that's $29,200, + the $16,000 purchase price is $45,200- still cheaper than I paid for Volt + electricity. If we went with the $2.50 cost per charge Chevy says is possible in some cities, Gas would have to go up to $5.16 per gallon to match the cost of Volt ownership. And remember that the price of electricity can go up, too. And also remember that all this is based on never driving the Volt far enough to be using the 35MPG gas engine instead of the 80MPG battery- if you start a new job commuting farther than 20 miles one way, or start having to drive the kids to all kinds of events, you could find the price tag escalating even faster. Unless the price of gasoline triples quickly, there simply aren't any scenarios in which it makes sense to buy a Volt.

That doesn't make the Volt a bad product. It's a good concept, and we have to start somewhere. And the price is bound to drop at least a bit as production ramps up. But stop the hype- it is not the salvation of the American automobile industry, or the environment.

And it does not get 230MPG.


ogre said...

Dunno about the physics (etc.). Personally, I find it highly questionable, given the shape of the Volt. The Aptera was designed ot be as aerodynamic as possible... and the claim there is 250-300 mpg equivalent.

Bottom line? I want to see the analysis, for each--and I want to see what Consumer Reports has to say about the claims.

Diggitt said...

Amen to Consumer Reports, still the fairest judge of all.