Jimmy was feeling a bit on edge, his cash wasn't enough to buy a decent car anymore because he hadn't prepared in advance. His bank cards were under his real identity, which could cause problems if he tried to withdraw money.
Counting the cash he had on him, Jimmy didn't plan to go for the cheapest car or resort to stealing a car by the roadside, so he decided to take a cab to the bus station to find a Greyhound bus.
Jimmy swayed as he returned to DC, carefully observing around Tom's safe house before making sure there was nothing unusual and going upstairs to open the door. Visiting this safe house repeatedly, it was likely already being watched. He stood out too much as an Asian.