FIGHTING AIR POLLUTION by sidelining old automobiles is a much-ballyhooed new environmental strategy among city and state governments. California, for example, has a program to give companies leeway on their factory emissions if they buy--and crunch--people's clunkers. On the surface, the reasoning seems sound. Since tailpipe standards have gotten tougher over the past decade, older cars spew out more ozone-creating chemicals and carbon monoxide than new autos.
IN REALITY, this misses a lot of superdirty cars. Studies by California officials and others, using roadside sensors, show that many newer vehicles spew out pollution if they are out of tune or otherwise poorly maintained. And compared with the pollution output of these dirty cars, differences between well-maintained new and mlder vehicles are relatively small. In its buyback program, for instance, Unocal recently obtained two mid-1970s Toyotas with identical emissions equipment. One left a pollution trail 100 times thicker than today's new cars; the other was as clean as a new car. In fact, University of Denver researchers have calculated that fixing the dirtiest 20% of the California fleet can cut overall emissions as much as crunching the oldest 60%.