Emissions Testing May No Longer Be Worth It, Study Shows

As older, higher polluting cars leave the road, traditional emissions testing may no longer be cost-effective for newer cars.

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A recent study by the National Bureau of Economic Research suggests that regular automobile emission testing may be approaching the point where it's no longer cost-effective to perform for the benefit gained. We may even already be at that point.

Emission testing is the bane of every car owner in areas that require it. Every time your car goes in can feel like a coin toss as to whether or not you'll be forced to pour hundreds of dollars into parts that don't seem to make a difference in how the car drives. But this hassle is responsible for huge air quality improvements in highly populated areas since California started emissions testing in 1984. Some other states and individual counties followed suit through the years, and air quality improved dramatically in highly populated areas that forced polluting cars to clean up their act.

However, the technology to reduce emissions has improved significantly since testing began in the mid-1980s. Dieselgate notwithstanding, today's cars run cleaner than ever. While the requirements for regular emission testing and repair have a significant effect on older cars, newer cars run so cleanly that there is little improvement. Even my Volkswagen Jetta Ute blasting around with its "check engine" light eternally on pollutes a small a fraction as much as older cars did. With an ever-increasing number of older cars making their way to the Great Junkyard in the Sky, the pollution problems these cars caused are going away with them. 

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Though California emissions may be up in the short term, it's still a small spike compared to how bad air quality used to be. Plus, electric cars, which don't pollute the air at all, are becoming more available and popular. In fact, electric cars are particularly well suited for the congested urban areas where pollution from fossil fuel burners tends to be the worst.

Some places that perform emission testing don't test older cars. For example, while Massachusetts requires all cars to undergo a safety inspection, there is a 15-year rolling exemption for the emission test. That means that my 2003 VW Jetta, "check engine" light and all, will be exempt from testing the next time it is inspected. This may seem backward, considering that older cars are the biggest polluters, yet are exempt. But unlike the fair weather state of California, conditions like terminal rust and crashes claim most Massachusetts cars before they age out of the emission test.

Every car sold in the U.S. since 1996 is equipped with OBD2, an onboard diagnostic system that monitors the car's operation and triggers the "check engine" light if it detects a problem. Most modern emission tests are little more than plugging a computer into the car to verify that its own systems are working properly. Although the study does not claim that testing of modern cars accomplishes nothing, it does suggest that at some point there will be a point of diminishing returns where gains of such testing will not be worth the cost of doing them. As of 2008, the last year of data the study processed, we were not yet at that point. But today, or soon, we could be.