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Determining the 'green-ness' of a car

Determining a car's 'green-ness' involves many factors, columnist Peter Gorrie argues.

Last week I wrote that driving a Chevy Volt was so much fun that thoughts of fuel-saving hyper-mileing flew out the window.

I also pondered whether this car — which runs up to 60 kilometres on battery alone before a small gasoline engine kicks in to power a generator — is truly “green.”

The unfortunate answer: “It depends.”

The real story of cars these days is choice.

Automakers have long offered a bewildering array of vehicles, arranged by brand, series and options. But those choices all involved internal-combustion engines and didn’t matter much environmentally. And, anyway, who in any showroom was thinking green?

Now, we’re faced with those previous choices, plus the option of going for much more efficient gasoline power, or hybrid, or electric, or, eventually, fuel cell.

Set aside driving style, since it applies equally to all cars. Likewise, how much energy is consumed and pollution emitted to produce each type of vehicle. Lithium-ion batteries get knocked on this score. But since they’ll have other uses when they’re no longer fit for cars, and can eventually be recycled, they’re likely on par with the rest.

The calculation also involves whether electricity for batteries is generated by dirty sources such as coal and nuclear, or cleaner options like water and wind. Battery power wins on this measure in most of Canada, although not in the United States and China.

Beyond that you have to consider how the car will be used.

Assume electric power is the least environmentally damaging propulsion.

All-electric cars, like Nissan’s Leaf or Mitsubishi’s iMiEV, win the green honours if you don’t drive more than their 160-kilometre range in one stretch. In any other case they’re second cars and, environmentally speaking, two cars are worse than one.

Except, however, if you live where two cars seem essential. Then, it’s marginally better to have battery power for shorter hauls and a gasoline vehicle for long trips.

Which brings us to plug-in hybrids, which do both jobs with one vehicle.

Among them, the Volt — with its 60-kilometre all-electric range but so-so fuel economy with the gasoline engine running — is ideal if, most of the time, your daily drive stays within that distance.

What if your typical day involves less driving? If you usually keep within 20 kilometres, you’d be greener with something like a plug-in Toyota Prius. It’s cheaper, contains fewer materials, requires less electricity and has significantly better fuel economy in hybrid mode.

Around Toronto, you’re hard-pressed to complete a Prius trip without burning gasoline: Advantage Volt. On longer trips, though, the Prius wins.

For a 200-kilmetre jaunt, after subtracting its battery-powered contribution, it will consume roughly 7.5 litres of gasoline. The Volt will use about 9. At 400 kilometres, the figures are 16 litres vs. 22.

The longer the trip, the more it becomes advantage Prius.

But you might prefer how the spiffier, faster Volt behaves – which raises the more ethical question of how plush and powerful do our cars really have to be.

To further confuse matters, as a reader noted: “We own a 2009 Honda Fit, which averages 4.9 litres per 100 kilometres on the highway and about 5.7 on town and city roads. It rates substantially better than the Volt. … I would not be surprised to know there are several models whose fuel consumption is superior to the Volt.”

By my rough calculations, on trips of fewer than about 275 kilometres, the Volt consumes less gasoline than a Fit. It does better than a standard Prius up to about 150 kilometres.

But then, you penalize the Volt for the electricity it requires and the Prius because it has far more components than a Fit.

And you hire an engineer to calculate that result.

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