Car is there for mainly for 2 reasons:
1. Transport to-from airport. Again, I am flying in DCA but outbound from BWI. Shuttles for 3 people will add up.
2. Trip to Shenandoah or anywhere around in NoVa/surrounding MD area.
I could manage a day rental for Shenandoah but what would be reliable for getting BWI without a car? Can I get a train from Union station in DC?