Benefit of driving a car

Fairfax to Philadelphia journey came down to 2 hrs and 45 mins. With additional flexibility of having the journey at ones own convenient time. It takes little more than 1/2 tank of fuel, which costs 18 dollars. Additionally, the tolls takes up to 13 dollars. Usually, it takes almost 5 hrs and 30 mins to finish the journey from source's doorsteps to destination's doorsteps. Journey can be broken into 3 parts:

Home to Viena -> Viena to Union Station -> Union Station to Philadelphia
  30 mins (+15mins)      45 mins (+15mins)         3hrs (plus 20 mins)
  Free                             $3-5                                $15-21

Comparison in total:
Public: 11hrs at a cost of (20+20) $40
Private: 5.5hrs at a cost of (31+25) $56
I think its worth spending additional 16 dollars that saves a lot of time and energy and allows for more flexibility.