Interesting logic! Even with the sunk cost of car, insurance, etc. it'd still have to be significantly cheaper or quicker for me to use it over a train, on which I can do other things. (I suppose its privacy is something, but not worth as much to me as the freedom to read or close my eyes.)
In the US, I'm about 45 miles from the nearest large city where I worked (many days) fairly briefly. I'd be about $400-500/month for commuter rail, commuter rail parking, and in-city transit passes. But the reality is that I'd be something close to $40/day driving (plus any parking) even given that I owned the car anyway.
I always took the train unless I was doing something in the evening--in which case the train was a poor option in general. (Once you got out of commuting hours there were only a few trains for the rest of the night.)
