carbon monoxide detectors for cars

Has anyone put a carbon monoxide detector in their car as a precaution?
There is a news story about police departments having problems with Ford Explorers exposing officers to too much CO-in a few cases the officer briefly passed out.

I looked into the story and found several sources for detectors intended for rough duty including cars. Apparently this is concern for some people.

Hasa anyone installed a CO detector in their car? What are your experiences with such a device?