This is a response I posted on the news site Pinyadda to a discussion regarding this article about the Chevy Volt. I feel it sums up my opinion quite nicely.

From speculation beforehand and Twitter for other news, there’s not really anything in there that I didn’t know or suspect.
It’ll be kind of hard to sell this car to groups outside of the first-adopters and techno-geeks with money to spare.

I’d love to have one for my wife to use; however, we need it to fit 3 carseats – so it’s out of the question. Why would I love to have one for my wife? She doesn’t go anywhere. Trips to her parents’ house, grocery store, or doctor are all very short. She’d be able to be in EV mode about 85% of the time she needs to go anywhere. The doctor’s office would be the farthest – and even round trip on that is only about 18 miles.

So, if she’s only driving an 18 mile round trip, that cuts another problem out – charging. Yes, it takes 16 hours to charge from “empty” on a 110V standard outlet. However, if your trip is only 1/2 the maximum EV range, then your recharge time is only 8 hours – so being plugged in overnight would put it back to 100% full.

Secondly, it doesn’t cost that much to get a 220V line put in. I’m not talking the fancy-pants chargers that are $2000; I just mean an outlet like an electric dryer has. Even if I paid someone else to put one in my garage, I’d be looking at about $200 for materials + labor. Do that, and a 50% recharge goes from 8 hours to 4.

Let’s say she wants to go to the nearest Target store. That’s about 32 miles away (I know!). In a perfect world, she’d be able to EV there on the 40 mile range, plug in, and EV home when she’s done shopping.

In today’s world with a Volt, there’s no place to plug in. So, she’d EV there, and then start to EV home. When depleted, the Volt would kick to gas, and she’d get home burning a little under a gallon of gas for the whole trip. Let’s call it a gallon for math’s sake.

She drove 64 miles on a gallon of gas. Did she get 64 MPG? Yes. HOWEVER, she also used some electric “fuel” for part of that. This is where the EPA struggles and you’ll see why.

How do you match up gallons and amps? That’s where the term ‘MPGe’ comes in. Miles Per Gallon Equivalent it what it stands for. A gallon of gas has 116,090 BTUs of energy in it. One kilowatt-hour of electricity has 3,412 BTUs of energy. The Volt has a 16 kWhr pack, that is allowed to discharge to 50% (to prolong battery life). 50% is 8 kWhr.

So, in this scenario, my wife used 1 gallon + 8 kWhr. We can’t add those, but we can add BTUs. 116,090 + (3,412*8) = 143,386 BTUs. Divide that by the BTUs per gallon, and we get…1.235. So she used as much energy as 1.235 gallons of gas to go 64 miles. That’s only 51.82 MPGe. She could easily get 51 MPG in a Prius, AND she’d have room to carry all 3 kids with her.

That’s where a point of contention about the MPG of the Volt comes in, and why people make such a fuss. GM is saying (and has been) that the car is only cost-saving if driven on EV for a VERY high percentage of miles (90% or more).

How often does my wife go to Target? Maybe two or three times a month. Otherwise, she’d be almost exclusively on electric. Thus, it’d work great.

But how much did such a trip as the Target run really cost? For me, electricity is about $0.11/kWhr after taxes, fees, and surcharges (base rate is $0.096/kWhr). So, the 8 kWhr she used cost $0.88, and the gallon of gas let’s say cost $2.75 – that’d make the total cost of the trip $3.63. 64 miles for $3.63 works out to a “Cost Per Mile” (CPM) of $0.0567.

Take the same trip in a Prius. My wife drives relatively conservatively; the Prius is rated for 51 MPG. She’d most likely be able to get about 55 MPG on the trip. 64/55 = 1.163 gallons of gas. At $2.75/gallon, that’s a cost of $3.198, or a CPM of $0.0499.

So the Prius is cheaper per mile even though the Volt used electric! Another point of contention about the MPG of the Volt.

Now, if we’re talking trips where the Volt uses NO gas, it’d chew up the Prius or any other car for CPM – FOR SOME PEOPLE. My electric is cheap; some people pay almost 3x what I do per kWhr. If you figure THAT rate, the $0.88 for electric becomes $2.64 – about the same cost as a gallon of gas. If that’s the case, why spend $41,000 on a car that doesn’t save you any money?

If you have your own solar setup, and you’re making free electric, then the CPM on the Volt would PLUMMET, especially if you never use gas.

Does that take care of just about everything? I hoped to also explain why there’s a love-hate relationship with GM and the Volt as part of that.

Way out of the field are the hypermilers such as myself, and the math shown above doesn’t take us into account at all. I don’t have a Prius; I have a car rated for 24 MPG average. I’m averaging 39 MPG; 62% higher than the rating of the car. If a hypermiler were to drive a Volt, would they get 40 miles of electric range, Or would they be able to squeeze 50? Maybe even 60 miles? Would they be able then to get better MPG when the Volt is running on gas?

These questions haven’t been answered yet because there hasn’t been enough time behind the wheel of one to find out.

Really, the only/best way the Volt is cost-effective is if you use it as an EV only, and have cheap electric. That’s the real bottom line.

The discussion on Pinyadda can be found here. I find Pinyadda to be a GREAT resource when it comes to not only news, but also to getting some “peer-review” of that news. Shouts go out to Cheryl Morris and the whole Yadda crew for putting together an excellent site!