Some of those Google cars that drive around photographing streetscapes and embarrassing moments have captured something extra — something that should embarrass major utilities. The cars were kitted out by University of Colorado scientists with sensors that sniff out natural gas leaking from underground pipelines. These methane-heavy leaks contribute to global warming, waste money, and can fuel explosions.

The sensor-equipped cars cruised the streets of Boston, New York’s Staten Island, and Indianapolis. They returned to sites where methane spikes were detected to confirm the presence of a leak. The results were released Wednesday by the Environmental Defense Fund, which coordinated the project, revealing just how leaky old and metallic pipelines can be, such as those used in the East Coast cities studied, particularly when compared with noncorrosive pipes like those beneath Indianapolis.

About one leak was discovered for each mile driven in Boston, Mass.:

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Boston gas leaks

EDF

The findings were similar in Staten Island, N.Y.:

Staten Island gas leaks

EDF

In Indianapolis, Ind., by contrast, about one leak was found for every 200 miles that the cars covered:

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Indianapolis gas leaks

EDF