I posted this in that post as well, but thought everyone might need to know this - especially the person whose alarm co told them because they didn't have gas appliances or heating (if you've got a garage, you need a detector!)
My dad's a firefighter, and he preaches and preaches about this. You will NOT ever smell the carbon monoxide. It is odorless and colorless. You won't know until it's too late. That's what is so scary about it. I agree -- def. get a CO2 detector!!!! Put one just inside the garage door that goes into your house (because cars give off CO2), in a room where there's a fireplace (they too give off CO2), and in the bedroom hallway, at the very least. It's a good investment.
Re: F/U: PSA: Carbon Monoxide Detector
Ditto. One of my high school classmates and his grandparents passed away due to CO exposure from a car accidently left running in the garage. It was such a tragedy.