http://www.wxyz.com/news/region/washtenaw-county/ann-arbor-to-fine-drivers-who-leave-their-vehicles-idling-beginning-july-1"It's called unnecessary idling and Ann Arbor cops will soon be enforcing in a whole new way. Considered a civil infraction, commercial drivers can no longer leave a vehicle idling unoccupied - or occupied for more than 5 minutes.
The 5 minute rule also applies to other drivers, but people are urged to cut off their engines after 10 seconds.
It's not just cars or trucks. The new rule applies to any vehicle with an internal combustion engine."Aircraft too, apparently.