How long does it take to die of carbon monoxide poisoning?

How long does it take someone to die or pass out from carbon monoxide poisoning in a car in a garage? My friend and I arguing about the scene in hot tub time machine where he falls asleep in his car with the engine on and passes out drunk with his foot on the gas pedal.
Update: Estimated time frame in a 2 car garage. I'm saying like 4+ hours my friend says an hour
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