Could I still die from carbon monoxide poisoning with new cars that have the catalytic converters?

Yes. If there I leak in your exhaust system with carbon monoxide leaking into your car interior and you are driving with closed windows for a long time you may experience carbon monoxide poisoning.
Why do you ask? If you are considering suicide, please phone your physician or the nearest suicide help line or go to the emergency room. These new cars, if run in the garage, are more likely to kill by oxygen depletion. It's still a bad way to go -- folks have left tape-recorded accounts of these experiences and I wouldn't wish it on anyone.