It's not worth it.

I always like public transport, but have absolutely nothing against private cars (except as noted above, when roads are much slower than rail, like the Van Wyck to JFK).

So after an experience a couple of years ago, I realized that there is no "credit" given at my company for saving $40-80, and much potential hassles can be avoided.

In 2001, I was on the RER train from CDG to Paris, around 5 am, just off an all night flight. I dozed off on the train and woke up when a kid was snatching my laptop and running off the train at some suburban stop.

I jumped up and chased, (I'm a New Yorker after all!), but by the time I caught the kid and got my laptop back, the train had pulled out with my bag on it.

Of course, I recovered the company's property (the laptop), and lost all my personal belongings, (which my company refused to reimburse me for, BTW...)

I've taken that train literally near 100 times, and think it's a fantastic train. But to save my company 40 euros? Nuh-Unh. Never again.