Well go and breathe it in and see what happens. If you can find a way of producing vast quantities of pure C8H18 and can get it to burn completely with a supply of O2 do let us know. In the mean time I won't throw away the 7 books that I've got sat on my desk that touch slightly on the subject of internal combustion.
It is true that CO emissions should be lower from a modern engine, that doesn't mean they're suddenly safe to inhale. That is of course ignoring the fact that filling your car up with CO2 isn't exactly a smart thing to do. Maybe ask your GP whether they would advise inhaling a lovely clean exhaust to Euro 4 standard?