A Colorado bill that is headed to the governor’s office would make it legal to leave cars running unattended if they have remote-start systems. State senators passed the update to the state’s so-called “puffer” law, which refers to the puffs of exhaust that come out of tailpipes during cold winter mornings. The bill would allow any owner with a remote-start system to warm up their cars without fear of getting a ticket. Although it is not widely known, it is currently against the law to leave a car running unattended. An average of about 50 “puffing” tickets per year are issued in Colorado.