A four-wheel drive vehicle with big tires, shaded windows, and a four liter engine sweeps onto the interstate and accelerates to seventy-five miles an hour. The few cars that still travel at the speed limit cower beneath its towering cabin as it weaves in and out. The knobby tires whine against the road, but with the windows are closed and the AC on, the passengers in their plush seats are as insulated and snug and secure as Darth Vader in his armored space suit and black plastic helmet. They feel safe in their big, new expensive SUV. But are they really?

An SUV is a kind of civilian tank, a suburban assault vehicle—designed to seem tough, powerful and intimidating. Like a tank, it's the product of an arms race, and the arms race has a history. The energy crisis of the seventies and early eighties launched a trend toward smaller, more fuel-efficient, less polluting cars. But the smaller and less expensive the car, the lower are the auto makers' profits—a condition not appreciated by their corporate leadership. So the managers of the auto industry, not perturbed by the social or environmental costs, devised two strategies for getting people into larger cars again.

The first strategy was an appeal to vanity. People like to imagine themselves as adventurers in the high desert, the wild Rockies or the Great Outback even when in fact most of their safaris take them to places no wilder than school, work, or the mall. Big tires and a four-wheel drive are about as practical for such adventures as cruise missiles or an 80 mm howitzer—but never mind. It is fantasy, not reality that sells such vehicles.

The second strategy the auto makers used to sell the SUV was fear. A small car, they correctly reasoned, provides less protection in a smashup than does a massive truck. So it ought to be possible to play on peoples' highway fears of twisted steel and mangled bodies—not directly, of course, but subtly—and initiate a stampede toward larger cars, vans, and ultimately huge passenger trucks.

This second strategy was wildly successful. Once enormous vehicles started appearing on the road, looming over ordinary cars and making it impossible for drivers to see around them, everyone began to feel intimidated. OK, people thought, so if you're driving a vehicle whose bumper is just about level with my windshield, then in order for me to feel safe and protect my family from your machine, I'll have go out and buy a bigger suburban assault vehicle of my own. Then I'll be safe. This, of course, is just the psychology of the escalating arms race. Once it takes hold, it becomes well nigh irresistible. But, of course, as with all arms races, it does not increase the general safety, because as soon as I get my really really big SUV, my neighbor is going to want to buy a really really really big SUV, and so it goes.

Thus we arrive at what in the lingo of strategic nuclear policy is called mutually assured destruction, M-A-D, for short. The assured destruction in this case, however, is not that we will be mangled in a tangle of really really really big vehicles, though that is a possibility, but that together we will create such smog, pollution and traffic congestion that we will wind up choking on each others' fumes. The engines of SUVs are much larger than those of ordinary passenger cars. They burn much more gas, and pour out proportionately higher quantities of volatile organic compounds, nitrogen oxides, carbon dioxide, carbon monoxide, and particulate matter. The results—increased smog, global warming, acid rain, and lung-searing ozone—will ultimately harm not only us and our world, but our descendants for many generations to come. America's great nature writer, Aldo Leopold, said it best: "too much safety seems to yield only danger in the long run."