What about carbon monoxide as a tailpipe emission? Is this not a GHG? [Alan]
Carbon monoxide is certainly toxic since when we inhale it, the molecule binds with hemoglobin irreversibly and thus prevents oxygen from reach our tissues. Therefore, sitting in a parked idling car in the closed garage can be lethal.
However, in terms of its impact on global warming visit: http://www.ghgonline.org/otherco.htm