The best way to get to Reims (€15, 2¼ hours, up to 13 daily), without a change in Paris, is by taking bus line 140 with Courriers de l’Aube (www.courriersdelaube.fr). Departures are from the very last bus berth to the right as you approach the train station; a schedule is posted. The bus station office is in the side of the train station.
There’s a huge free car park a couple of blocks south of the old town on bd Charles Délestraint – take rue de Turenne, cross the roundabout, turn right and then left. Even closer to the centre is the free car park on place de la Tour, a couple of blocks north of the cathedral. Close to the train station, Europcar rents cars.
Troyes is on the rather isolated train line that links Mulhouse (€56 to €115, four to six hours, 13 daily) in Alsace with Paris Gare de l’Est (€11 to €28, 1½ hours, 10 to 14 daily). To get to Dijon (€25 to €35, two to four hours), change in Culmont or St-Florentin-Vergigny.