Things are not always what they seem to be.

For example, which car is the greater threat to the world: the Chevy Tahoe, or the India-made Tata Nano?

The answer should be obvious. The Chevy Tahoe is a huge monster that weighs 5,500 pounds and is nearly 17 feet long.

The Tata Nano, on the other hand, is just a mite, barely stretching 10 feet. It's too lightweight to be believed.

More convincingly, the Tahoe gets only about 16.5 miles to the gallon in combined city/highway ratings, while the minuscule Nano gets a whopping 47 miles to the gallon.

And, as you might guess, the Chevy spits out a lot more bad stuff into the air. Stuff that creates the haze that feeds global warming.

So why is the Tata Nano a much greater threat to the earth? Why will it encourage global warming?

It's all in the price.

Chevy Tahoes cost around $30,000, depending on the model.

But those cute little Nanos are on the market for only $2,500.

That's only 8% as much as the Tahoe, and that spells big trouble for the health of the planet.

At $30,000 a pop, few people in the world can afford a Tahoe. Not in Europe, where gasoline prices are flirting with $6 a gallon. Not in Asia, where the middle class brings home the equivalent of $5,000 or so a year. And not in Latin America, where annual paychecks of $7,000 place you firmly in the middle class.

So there aren't going to be many Chevy Tahoes out there polluting the air and encouraging global warming.

But the Tata Nano at $2,500? Lots of people are going to be able to afford that.

There are over 200 million middle-class Indians who can handle the price of a Nano. (Nanos are to the donkey what Model Ts were to the horse.) And don't forget China. There are over 300 million folks who could easily buy one. Beijing isn't building all those super highways for walkers. And the Chinese bicycle industry is already in a state of collapse.

With gas already topping $6 in parts of Europe, half the Continent will leap at the change to dump a Volkswagen for a Nano. That's another 250 million potential buyers.

Throw in North and South America, and you're talking another 300 million cars on the road.

If you tote that up, it comes to over one billion drivers: 700 million newbies and 300 million downsizers.

There's going to be a lot of bad stuff hitting the skies.

Although it wasn't intended that way, the Tata Nano and its imitators will really be heating things up.

So stop yelling at the few driving Chevy Tahoes. Downsize your outrage and start looking at the cute little cars that may be the biggest threat of all.

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