2011 Chevrolet Volt Long Term Road Test


2011 Chevrolet Volt: "Fuel" Economy Update 2

March 02, 2011

2011_chevrolet_volt_det_ft_11081010_717.jpg

Welcome to the second update of our 2011 Chevrolet Volt's fuel economy -- errr, electricity consumption. Well, it's both, actually.

The Volt's cost and consumption story is complex, so I'm trying something a bit different with this particular monthly summary. It's a work in progress.

Because you asked for it, I've added cost per mile calculations using national average prices for gasoline and electricity. You'll also see the cost per mile with California average gasoline and electricity prices, though the price many editors pay at home is far higher than this.

Some of you expressed an interest in seeing the "apparent" mpg, looking at gasoline used over all miles driven and ignoring electricity. It's a bogus figure from an overall cost and consumption perspective, but it has a use if all you care about is reducing our dependence on gasoline that's derived from oil. I hesitate to say imported oil, because some of it is domestic, but you get the idea.

Before we get to that, here is the consumption and range breakdown, with gasoline consumption figured over the gasoline-driven miles and electricity consumption figured over the battery electric miles.

2011 Chevrolet Volt

Best

Worst

Average

Electricity (*kWh/100 mi)

26.2

52.0

35.6

Electric Range (miles)

46.4

25.8

36.6

Gasoline (mpg)

39.0

29.8

33.7

* Remember, smaller is better with the kWh-per-100 miles unit

Here is how these compare to EPA consumption and range estimates.

2011 Chevrolet Volt

Best

Worst

Average

EPA

Electricity (kWh/100 mi)

26.2

52.0

35.6

36

Electric Range (miles)

46.4

25.8

36.6

35

Gasoline (mpg)

39.0

29.8

33.7

37

That's right, our Volt is beating the EPA's estimates for range and electricity comsumption but is falling short of the expected gasoline consumption.

The ratio of battery-electric miles to total miles is called the Utility Factor in engineering circles. It sounds weird until you associate the word "utility" with electric utilities. We were breaking in our gas engine during January, so the percentage of battery-electric miles (the UF) was a bit low. We brought that up significantly this month, as you can see here. More charging means fewer visits to the gas pump, so the "apparent" mpg goes up accordingly.

2011 Chevrolet Volt

Jan

Feb

Overall

Utility Factor (% EV miles)

31%

60%

44%

“Apparent” MPG (ignoring electricity)

49.2

82.0

59.8

Cost per mile (US average prices)

8.1¢

7.0¢

7.6¢

Cost per mile requires a bit of clarification. The February cost per mile fell even as gas prices went up because we spent more time running off the batteries. This works out with the current national average electricity prices, but it doesn't hold true at any electricity price, as we will see later.

For the record, the national average residential price for electricity used here is 11.7 cents per kilowatt-hour. The DOE's official figure hasn't been updated since Nov 2010, so we're using that figure in January and February. This isn't a huge problem because electricity prices don't bounce around like gasoline prices.

But gasoline prices do fluctuate--a lot. Fortunately, the statistical data is also updated quite rapidly. For February we used the current national average premium fuel price, $3.633 per gallon. Last month's national average of $3.409 was used for January. Yeah, if you didn't already know it, the Volt requires premium.

For reference, here is the theoretical cost per mile of a couple of popular Hybrids, calculated using national average prices for regular unleaded. I say theoretical because you have to match the EPA combined rating to make these numbers.

2011 Toyota Prius (50 mpg comb)

6.2¢

6.8¢

6.5¢

2011 Ford Fusion Hybrid (39 mpg comb)

7.9¢

8.7¢

8.3¢

So far these figures are based on national prices, but electricity varies wildly by state--even within states or neighborhoods. It should be no surprise that California gasoline prices and electricity rates are more expensive than the national average.

2011 Chevrolet Volt

Jan

Feb

Overall

Cost per mile (Ca. average prices)

8.9¢

8.2¢

8.6¢

Cost per mile (charging at my house)

10.6¢

11.8¢

11.1¢

California electricity --15.2 cents

California premium gasoline -- $3.967 now and $3.632 a month ago.

Electricity at my house -- 31 cents (SCE tiered rates, highest tier)

Note that the cost to plug in a Volt doesn't make sense at my electric rates. See how the cost per mile goes up during February, the month we plugged-in our Volt more of the time? In my specific case, the more battery I use, the more I pay. There is a tipping point for the price of electricity, and I live beyond it. I can't tell you what that point is with precision because the never-ending flux of gas prices makes it a constantly-moving target.

That's enough nerding for one day, don't you think?

Dan Edmunds, Director of Vehicle Testing @ 2,865 miles

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Edmunds Insurance Estimator

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

$121 per month*
* Explanation
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