The San Diego Metropolitan Transit System is buying up to 350 compressed natural gas fueled 40-foot low-floor buses made by bus manufacturer Gillig and up to 165 of bus maker New Flyer’s 60-foot low-floor articulated CNG buses through 2017. The transit system will be investing more than $343 million for these fleet acquisitions. This will put the agency on pace to retire the last of its remaining diesel buses.