I think the CO level would have been pretty close to nil.  
I would hope so, but the reason I raise the issue is that my encounter with CO came from use of a miner's carbide lamp in a partially enclosed space with a volume about that of a typical automobile.  The flame on the carbide would have had a length equivalent to one or two typical candles.  The result was a raging headache which dissipated upon exposure to fresh air.
I checked for some public health information about carbon monoxide on Wikipedia.  The estimate is that about 40,000 people seek medical attention for CO poisoning annually in the US.  Over a ten year period (1979-88) there were 30,244 unintentional fatal cases of CO poisoning, as well as 25,889 suicides.  The article mentioned that catalytic converters scrub about 99% of the CO from car exhaust, although an engine running in an enclosed space can still cause problems.  Far fewer people use car exhaust as a means of suicide because of this.
end of rant - stepping down from soapbox.