The fire truck, lights flashing, with at least six fireman all suited up with oxygen tanks and masks and the hazmat equipment and a huge fan, all came. We have a copy of their incident report. I like your idea of including a copy with the boo-hoo letter.
Apparently, our new insulated garage door doesn't leak the emissions from my 1997 car to the outdoors the way our old dried out wood door did. The car did pass it's recent emissions test, but emits enough to eventually waft up to our CO monitor and create a piercing alarm. I'll be leaving the garage door a bit longer when I drive in now.
When the alarm sounded, we carried the plug in alarm outside to the fresh air, where it stopped. Then we returned inside and went down the basement stairs, when it started again. We called 911 and were told to evacuate the premises. It could've been our oil hot water tank or my dryer run by a propane tank, either causing repair/replacement bills. So, if it's just my car, that's so much easier to solve.