Case Study, Ron Montoya - 2011 Chevrolet Volt Long-Term Road Test
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2011 Chevrolet Volt Long Term Road Test

2011 Chevrolet Volt: Case Study, Ron Montoya

March 25, 2011

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Unlike other cars, the case for the "dual-fuel" 2011 Chevrolet Volt depends greatly on an individual driver's situation. Length of commute, driving conditions, driving style -- the amount of electric-only driving and the need for gasoline depends greatly on these factors.

For this reason we can't use the overall average consumption approach we use for single-fuel pure gasoline cars. I'm including the Toyota Prius here because it uses exactly zero electricity from outside sources--there is no plug through which the battery can be pre-charged.

With those cars, total miles divided by total gallons works great, and we can co-mingle long commute data with short commute scenarios and still get a good randomized result that we can compare to the EPA's combined MPG estimates. There are differences in individual circumstances, of course, but it has been that way so long that we're all able to relate averages to our own situation.

But that doesn't quite work for the Volt. Someone who lives 2 miles from work will have a very different opinion from someone who lives 50 miles away. The former may not use any gasoline while the latter may use a lot. The differences are much larger here.

So we're doing something different with our Volt. We're going to collect "case study" data from different individuals. We'll choose the subjects carefully so each has a different sort of commute and we'll break out their results separately from the mooshed-together averages. Each will keep the Volt for a solid week. We'll do this once a month.

Case study #1

Subject: Ron Montoya, Consumer Advice Associate

Commute distance: 5.9 miles each way

Commute type: 90% congested freeway, 10% surface streets

Utility company: LA Department of Water and Power (LA DWP)

Before we get to Ron's case study, here are the overall figures for all of the Volt's miles so far. We're using the following current national average prices here: 11.7 cents per kWh, $3.829 for super unleaded, $3.561 for regular unleaded.

Utility factor: 47% (47% of total miles in battery EV mode)

Miles driven: 3,000.2 - 1399.6 electricity, 1600.6 gasoline

Average electric range: 37.6 (from full battery charges only)

Fuel used: 491.4 kilowatt-hours of electricity and 47.7 gallons of premium gasoline

Apparent MPG: *62.9 mpg (total miles/gasoline burned, ignoring electricity consumed)

Actual gasoline consumption during gasoline engine operation: 33.6 mpg

Electricity consumption on battery power: 35.1 kWh every 100 miles

Overall cost per mile: 8.0 cents

Prius cost per mile: 7.1 cents (@ 50 mpg EPA combined)

*Remember, the Apparent MPG figure is a bogus factor from an overall cost and environmental impact standpoint, but we're including it for those who are primarily interested in reducing the amount of oil-derived gasoline they use. The electricity used in place of gasoline comes from somewhere and has its own cost, but certain potential Chevy Volt and Nissan Leaf customers seem happy to ignore this. Rightly or wrongly, the Apparent MPG is simply and exclusively associated with gasoline consumption or the lack thereof.

On with the show...

It must be said that Ron is a renter and cannot charge the Volt at home. So he plugged it in at work instead. Almost all Volt owners will charge at home -- few workplaces have a charger like ours, but by charging at just one end of his commute we're still able to simulate the real-world costs of real-world people. To that end, we're using his home electric rates to simulate what an actual homeowner in his situation would have paid.

Here are Ron's figures, measured over a full week and using his utility cost (14.76 cents per kWh, including all taxes and fees) and California's current average gasoline prices ($4.189 for premium and $ 3.993 for regular).

Utility factor: 89% (89% of Ron's total miles were driven on outside electricity)

Total miles driven: 194.1 - 172.9 electricity, 21.2 gasoline

Average electric range: 42.0 (from full battery charges - partial charges excluded)

Fuel used: 54.1 kilowatt-hours of electricity and 0.75 gallons of premium gasoline

Apparent MPG: *259.8 mpg (total miles/gasoline burned, ignoring electricity)

Actual gasoline consumption during gasoline engine operation: 28.4 mpg

Electricity consumption on battery power: 31.3 kWh every 100 miles

Overall cost per mile: 5.7 cents

Prius cost per mile: 8.0 cents (@ 50 mpg EPA combined)

Things to take away from this...

A Volt running at a 47% Utility Factor is 13% more expensive to operate than a Prius on a cost per mile basis, even at national average prices.

Ron's short commute allows him to drive on outside electricity 89% of the time, so for him the Volt is a full 28% cheaper to operate than a Prius.

Ron's performance on gasoline fell short of the EPA estimate (28.4 mpg versus a rated 37)

That said, Ron will use only 3 gallons of gas per month

Ron's electricity consumption beat the EPA estimate (31.3 kWh per 100 miles versus 36)

Ron household used 242 kWh last month. A full month of Volt use will add 232 more kWh per month, essentially doubling electric bill. A portion of the Volt's additional electric load will therefore be charged at the LADWP's higher "tier 2" rate. But in his case that rate is only 1.5 cents higher than tier 1 and the overall cost per mile won't change much. In winter there's no price difference at all between tiers 1 and 2.

Moral of the story: Purchase price aside, the Volt pays off handsomely for Ron and his 5.9-mile commute because he can run on electricity much of the time and his electricity is fairly cheap.

Dan Edmunds, Director of Vehicle Testing


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