2011 Chevrolet Volt Long Term Road Test


2011 Chevrolet Volt: December (And One Year) Fuel Economy Update

January 10, 2012

2011_volt_1600_chargecord_damp.jpg

December represents our twelfth month with the 2011 Chevrolet Volt, and that makes this update a one year summary of our Volt's thirst and, well, whatever Bender calls it when he needs a jolt.

In the past 12 months our Volt has amassed just over 13,000 miles. That number could have been higher if we had encouraged more long road trips, but the number of long trips 20 people take in a year is far more than a single owner would take, and that would have skewed the results too far in the gasoline direction, which is most definitely not the Volt's sweet spot.

As it was our Volt was already being driven by staffers who live too far away to make best use of the EV part of its split personality (raises hand). Combine that with the handful of long trips it did make and you get our observed Utility Factor of just 43 percent. The Society of Automotive engineers reckons a plug-in hybrid with 35 miles of rated range should run on electricity 58 percent of the time in the hands of a typical consumer. We reckon they're right.

2011 Chevrolet Volt

Best

Worst

Average

EPA

Electricity (kWh/100 mi)

22.9

58.4

34.2

36

Electric Range (miles)

54.6

23.5

37.3

35

Gasoline (mpg)

42.6

21.8

34.3

37

Our average electric range (from fully charged to fully discharged) was 37.3 miles, and that was derived from 96 data points. Twice that many partial discharges can't be counted because the car was plugged in again before it ran out of juice -- which we encouraged because that's what you'd do if you were trying to run on electrons as much as possible.

In perfect semi-traffic conditions I managed to smash through the 50-mile barrier twice -- 54.6 and 54.3 miles on consecutive charges -- though no one else did. In my case, perfect conditions meant nearly-clogged freeway traffic that rolled steadily at 35-50 mph without any stopping or sudden speed changes.

We also beat the EPA's estimate for average electricity consumption. Our average was 34.2 kilowatt-hours used every 100 miles instead of the rated 36 kWh/100 miles.

On the other hand, gasoline fuel consumption was worse than the EPA combined rating, 34.3 mpg actual versus 37 mpg rated. Before you say we didn't drive enough long-distance highway miles, please remember that hybrids do better in the city, where speeds are lower, regenerative braking is in effect and electric motors are more efficient. Note that our longest e-range occured at sub-freeway speeds. At regular freeway speeds the Volt's engine is doing two things at once, generating electricity on the one hand while assiting with direct mechanical propulsion with the other, which means it's working that much harder.

What all this points to is an EPA gasoline consumption rating method that is equally optimistic when this plug-in is burning gasoline as it is when certain brands of traditional gasoline-powered cars are on the dyno rollers. Maybe the EPA and NHTSA should take another look at their methodology. It's hard to see how we would beat electricity by 5 percent and miss gasoline by 8 percent, but we did.

On the other hand, human nature could explain it. Think of the conversation in your head going like this: "I'm out of juice and am now burning gasoline. I have no more range to maximize. The videogame is over. I need no longer drive like Ed Begly Jr. Time to make up for lost time."

Comparing notes with others in the office, the Ed Begley Jr. effect seems to be a real thing.

2011 Chevrolet Volt

Sept

Oct/Nov

Dec

Overall

Utility Factor (% EV miles)

49%

53%

51%

43%

Apparent MPG (ignore electricity)

71.9

70.8

73.3

59.8

Cost per mile (US average prices)

7.1¢

7.4¢

7.2¢

8.1¢

(Cal. average prices)

8.1¢

8.4¢

8.0¢

8.9¢

Popular hybrids, for reference

Sept

Oct/Nov

Dec

Overall

2011 Toyota Prius (US average prices)

6.8¢

6.6¢

6.7¢

7.1¢

(Cal. avg prices)

7.6¢

7.3¢

7.4¢

7.6¢

2011 Ford Fusion Hybrid (US avg prices)

8.7¢

8.4¢

8.7¢

9.1¢

(Cal. avg prices)

9.8¢

9.3¢

9.5¢

9.8¢

I found a flaw in my October/November data, in which I left some electricity consumption out of the cost calculations. The gray boxed have been revised upwards, which, frankly, makes them make more sense.

In the end, the cost to operate our 2011 Chevrolet Volt in National Average terms worked out to 8.1 cents per mile. As it happens, a Toyota Prius would have cost a penny less per mile and a Ford Fusion a penny more, assuming both spent the year running at EPA combined. Any hybrid owner will tell you this is unlikely, indeed.

And that's at a yearlong Utility Factor of 43 percent. One column to the left, where December's average UF was 51 percent, the cost per mile was 7.2 cents. And if you can achieve the SAE's predicted 58 percent UF, the cost per mile drops into the 6-point-something cent range. And it'd be far less than that if you lived in Washington State, where they practically pay you to take electricity off their hands.

Bottom line: the cost to operate the Volt (and whether it makes economic sense to you or not) is entirely dependent on how far you drive every day between plug-ins, how much of that is wide-open freeway and what you pay for electricity.

Furthermore, the Volt's medium sized battery takes about 12 kWh to fill from empty on any given day, which is totally doable overnight (or during a standard 8-hours-plus-lunch workday)on standard 120V electricity from a regular outlet. Pure electric cars with larger batteries can't say that; they need the 240V charger.

Of course, you first have to swallow the price of the thing. Factor that in and the stronger gasoline hybrids may come out cheaper in the long run.

Yeah, there's math involved.

Dan Edmunds, Director of Vehicle Testing

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Edmunds Insurance Estimator

The Edmunds TCO® estimated monthly insurance payment for a 2011 Chevrolet Volt in VA is:

$100 per month*
* Explanation
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