It's what you can't smell that will kill you!
My cousin and I were driving to Pittsburgh once with his some of his beer equipment in the back of my station wagon. We stopped for lunch. When we got back in the car, we immediately began feeling very light-headed. I yelled, "Get out of the car!" as I grabbed the door handle. We both stumbled out gasping for air. Popped the hatch and found one of the CO2 bottles heavily frosted. It had sprung a leak while we were eating and filled the car.
Never smelled a thing.
2011 Mustang GT, Sterling Gray Metallic, 401A Brick Red, 3.73, Brembos, Glass Roof
"All I can do is laugh. The tears dried up long ago."