Those funny-looking cars that Google sends around to map the streets may soon start mapping something else: methane leaks. Methane, a greenhouse gas that contributes to global warming, can also pose fire risks, International Business Times writes. And one recent study found that about $90 million of Boston-area gas escaped into the air in 2012. Finding leaks is the first step to fixing them, so researchers at Colorado State University fitted air samplers onto the front bumpers of three Google cars before the drivers set out on routes through Massachusetts, New York, Vermont, and Indiana. The researchers found that cities with older gas pipelines leaked about 25 times more gas and argue in a study published today in Environmental Science and Technology that the cars could be a fast and inexpensive tool for tracking down leaks.