I have been driving PIU vehicles now with my Sheriff's Office for several years now. What seems strange to me is it's not all the vehicles. My department has at least a couple hundred of these vehicles driving around and I have heard of one PIU being turned in for the exhaust fumes in the cab. Whatever is causing it is not consistent, and is either occuring as a manufacturer defect or being created with wear. I personally have not had this issue and my units idle forever, probably more then drive time due to checkpoints and other patrol activity.