I was going through the owner's manual of my 04 Civic and got to see this piece of information. It is clearly mentioned that Carbon Monoxide will enter the vehicle but should not pose any issues if the car is maintained properly. The warning in the box says that it can cause unconsciousness and even kill the occupants. This is something I am not aware of. I was of the impression that this toxic gas entering the car may be due to some issues in the car itself. Any thoughts, guys?