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Latest data sheds light as the Chevrolet Volt testing nears completion

Consumer Reports News: August 11, 2011 10:38 AM

We’ve been testing and living with the Chevrolet Volt for seven months now, exposing it to the rigors of both winter cold and summer heat. As we count down to the complete test in the October issue, we want to share some insights from our experience with this intriguing car.

Overall, the Volt is an ingenious concept, essentially an electrically powered car with a backup gasoline engine for when you run out of electric power. That 1.4-liter engine acts as a generator, maintaining the battery at a sufficient state of charge to preserve most of the electric drive experience. Most importantly, it allows for an extended driving range. And even then, it’s not like you are left with a puny 80 hp, 1.4-liter engine. The car retains the instant torque of an electric car, shuts off at idle, and recaptures some energy in regenerative braking while coasting.

During the winter months, the Volt delivered only about 28 miles on average of electric-only driving and as few as 21 miles when it was brutally cold outside. Most of the range-sapping could be attributed to the heater. Lately we’ve been getting almost 39 miles on a regular basis and yours truly posted 51 miles nursing it along on country roads with the air conditioning switched off. We’ve found that staying off the expressway and keeping the Volt at 40-45 mph on rural roads maximizes its electric range. Our average however rests at 35 miles, which is also what the Environmental Protection Agency (EPA) found.

It’s impossible to assign a single gasoline-use figure to the Volt, because average miles-per-gallon is a function of trip length, or the frequency of charging. On short trips, the Volt uses no gasoline at all. Trips that run down the battery and cause the engine to kick in start cutting into the electric-powertrain advantage and return fuel economy closer to--and sometimes not as good as--some of the most frugal conventional cars.

Electricity-wise, we’ve been averaging 2.93 miles/kwh, which translates to 99-mpg equivalent (MPGe) using the EPA’s formula. It takes a little more than four hours to recharge using a 240-volt charger and about nine hours using 110-volt household outlet. A full charge takes about 12.7 kwh of electricity.

In order to come up with a single composite figure for the Volt, we assumed a 50-mile daily trip, including 35 miles on electric power. Based on that scenario, our formula yields a 70-percent electric usage, which is how we weighted the electric to gas ratio. The EPA assumes 65-percent electric ratio and GM reports that actual Volt buyers do 66 percent of their driving on electricity. Electric consumption is represented in terms of MPGe according to the EPA’s formula. Not everyone agrees on the EPA formula, but for now it’s an accepted convention.

As for gas use, we averaged 29 mpg overall on gas-only mode and 36 mpg on the highway, which is merely good. Oddly, the Volt requires premium fuel, further encouraging Volt owners who expect to save on operating costs to minimize gas usage and charge frequently. If your typical driving distance is less than 40 miles a day, and you can “top it off” between trips, then you will rarely have to visit a gas station.

Cutting to the chase
Will it save money in running costs? The answer is yes, if the Volt is used for short distances and no if used for long drives (see chart below). But unlike the all-electric Nissan Leaf, the Volt provides an extensive range and the peace-of-mind of not getting stuck.

When will it not save money? If electricity in your area costs 22 cents/kwh, running costs will equal a Toyota Prius, the Volt’s most direct competitor and the car most often traded for the Volt. Here’s a chart that includes other alternatives:

Cost per mile Cost for 30 miles Cost for 70 miles
Chevrolet Volt (2.93 mi/kwh for 35 mi., then 29 mpg) 3.75 cents ev;
13.69 cents gas
$1.13 $6.14
Toyota Prius (44 mpg) 8.6 cents $2.59 $6.05
Honda Civic Hybrid (40 mpg) 9.5 cents $2.85 $6.65
Hyundai Elantra (29 mpg) 13.1 cents $3.93 $9.17
(ev = electric vehicle mode)

Underlying assumptions: Volt calculation based on 35-mile electric range followed by premium fuel use; electricity at 11 cents per kwh (national average); gasoline at $3.80 per gallon regular, $4.00 premium. No stops for recharging. Overall fuel economy from CR instrumented tests.

Our well-equipped Volt’s sticker was $43,700. That’s not cheap for a small car with only four seats, but new technology tends to be expensive. With the $7,500 federal tax credit, the car can become a $36,100 car--about $3,000 more than a loaded Prius. Whether that works for you is an individual choice.

We’ve already praised the Volt’s strong-and-seamless acceleration and quietness. Putting aside fuel-economy and electric drive considerations, as a car, the ride is taut and compliant and handling is secure and responsive. The seats are supportive. On the debit side, the Volt is only a four-seater, so practicality is limited. Visibility is problematic, getting in and out of the low slung car can be challenging, and some controls are confusing. GM says the heater will be stronger in 2012 models.

The Volt can save you money on running costs if charged often enough to maximize its electric capability. Plus, it doesn’t suffer from the range limitation of other EVs such as the Nissan Leaf. Clearly, for the prudent consumer, and for the long-distance commuter, a Toyota Prius is a proven and established entity. But for those who feel, a Prius is old-hat, the Volt certainly pioneers a new genre and goes a step further.

Gabe Shenhar


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