Drive with window open to stop carbon monoxide poisoning?

My mother always told me this as a kid. She insists that driving with the window open a half inch or so will save you from being ged by your own car. I have never heard this anywhere else, I only though that was possible if your tailpipe was blocked. I don't see how you tailpipe could suddenly become blocked while driving down the road. Any ideas if this could be true? Im sick of hearing her constantly bugging me about it. I don't like having the window open to long in winter its awful cold where I live. After years of driving Im still alive. Im thinking its one of those myths that people insist is true.