Platooning vehicles---those traveling in a line with short intervehicle distances---experience reduced aerodynamic drag. Given a set of vehicles with origin/destination nodes/times, we model and solve the combinatorial optimization problem of routing them to their destination on time while using the least amount of fuel. Common approaches for routing platoon-capable vehicles often decompose the platoon coordination and subsequent routing into separate problems. Our model addresses both problems simultaneously. We study the effect of coordinating routing in various road networks and different assumptions on vehicles' willingness to wait in order to form platoons.