puffer
n.— «Police Chief Gerry Whitman said officers also will be on the lookout for “puffers”—unattended cars puffing exhaust while warming up. The cars often are stolen for joy rides or wind up being used in crimes. Anyone who leaves a car running unattended faces a traffic citation and a fine. Ironically, on the same day Denver police issued the puffer warning to motorists, an unmarked police car was stolen while warming up.» —“Commuters contend with storm’s icy aftermath” by Sean Kelly, Ann Schrader Denver Post (Colo.) Nov. 30, 2004. (source: Double-Tongued Dictionary)