The 2012 Toyota Prius gets the best EPA-rated gas mileage--50 miles per gallon combined--of any non-plug-in car sold in the U.S.

But the Prius hybrid sometimes gets a bad rap.

At least some of it is due to the notorious (and very funny) South Park episode in which a deadly attack of Smug afflicts the little mountain town whose residents all drive a hatchback called the Pious.

With its top-of-the-list gas mileage, a Prius hybrid is clearly a step in the direction of driving green--and all journeys begin with the first step. But by itself, buying a hybrid isn't enough.

Here are five reasons that just driving a Toyota Prius won't make a notable dent in the enormous task of saving the planet (however you may define that).

(1) Burning gasoline generates more carbon dioxide than driving electric (in most states)

While their results vary in degree, two studies conclude that in many states, driving a mile on grid power produces less "wells-to-wheels" carbon than driving a mile in a 25-mpg gasoline car.

The 50-mpg Prius is slightly better in a few states with the dirtiest grids--like North Dakota and West Virginia--that use almost entirely coal.

But the grid will slowly get cleaner over time, with no new coal plants, more natural gas, and a slow but steady growth in the use of renewable energy.

So electric cars are mostly better now, and will get even cleaner over time--unlike the Prius.

2012 Toyota Prius Plug-In Hybrid, production version road test, San Diego, CA, Jan 2012

2012 Toyota Prius Plug-In Hybrid, production version road test, San Diego, CA, Jan 2012

(2) Using less gasoline is not as good as driving less

If you buy a 2011 Toyota Prius for a round-trip commute that's 100 miles, you're still burning 500 gallons of gasoline a year. Whereas if you could walk, bicycle, carpool, or take mass transit to work, you wouldn't.

Unfortunately, 60 years' worth of U.S. zoning laws have trapped many of us into suburban sprawl that keeps commercial buildings--be they stores or offices--miles away from residences.

That means a car becomes necessary even to get a gallon of milk. And outside a few major cities, mass transit is unappealing to nonexistent.

While most Americans say they would like to live much closer to their jobs, mixed-use neighborhoods that prioritize walking, biking, and mass transit over single-occupant cars are often still viewed as something akin to Socialism by local officials. 

Never mind the traffic, in other words--not our problem--and besides, expanding roads generates jobs!

2012 Toyota Prius Plug-In Hybrid

2012 Toyota Prius Plug-In Hybrid

(3) Even a Prius can't keep pace with global car growth

We now have 1 billion vehicles on the planet, and by some estimates, we'll have 2 billion or more by 2050. In other words (well, just one word): China.

Today, only a tiny number of China's 1 billion-plus people have cars. That will change.

So just to stay in the same place, the efficiency of every vehicle has to double--to Prius levels or more.

But many scientists say that to stem the predicted effects of climate change, we must cut our carbon output up to 80 percent from today's levels. That will bring far more radical changes.

(4) Modern lifestyles encompass much more than just car emissions

One of our favorite book titles lately is Time to Eat the Dog? The Real Guide to Sustainable Living, whose authors measured the environmental impact of modern lifestyles.

Scout the dog, rescued by Rondout Valley Animals for Adoption, Accord, NY; photo: Jay Blotcher

Scout the dog, rescued by Rondout Valley Animals for Adoption, Accord, NY; photo: Jay Blotcher

They conclude that adopting an existing animal and spaying it has an impact on your family's carbon footprint.

We don't recommend cooking your cat, but if you're thinking about your pet having litters of adorable furry kittens or puppies--think again.

More than that, cut out airplane flights. They comprise up to 80 percent of a frequent traveler's carbon footprint.

(5) Family planning and contraception may be more cost-effective

Far more impactful than spaying your pet would be making effective family planning services and contraception globally available.

A London School of Economics report suggests that family planning can eliminate atmospheric carbon for $6.70 per ton, against conventional technologies to improve vehicle fuel efficiency that can cost up to $31.70 a ton.

Forgo the Prius, and spend that money donating to Planned Parenthood? It might be more effective.

For more along these lines, see also our discussion of why gas-guzzlers will always be with us.


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