Carbon Monoxide is pretty dangerous and can kill someone quite easily.
http://www.extension.iastate.edu/Pag...ns/CO/co1.html
While getting a little car exhaust mixed with lots of fresh air from your car window shouldn't do anything to you, it certainly can't be good for you....
__________________
Uncle Sam
"What the hell is up with all the gauges?
Calling Captain Kirk, your ride awaits... Phasers on stun...."