CO from running Dart in garage with door open

Hey guys,
I admit that Im one of those guys who never think about CO gases. I do have a detector in my house by the bedrooms, but other than that, never think about it.
I had a couple power outages this year and was considering getting my first portable generator. Mostly just for sump pump and fridge/freezer. Since I never had one, I was unaware of all the safety precautions that one must follow. Most importantly, not to use in the garage, but at least 15 feet from the house.
Got me thinking about when I start up the Dart and just let it run for 10-15 minutes until it reaches op temp in the garage with door open. The exhaust is pointed out, but Im sure alot of it blows into the garage. I assume many of us do this, especially in the midwest rust belt. Am I wrong? Am I putting myself at danger?
As of now, the car is up on stands as Im replacing all suspension and brakes so I cant even back out.
Am I oveethinking this cuz of my new found generator knowledge?
Thanks for any advice.