A roller coaster is being designed for a new theme park. Two trains are on the track at any given time. One train is being unloaded/reloaded while the other is moving along the track. The track itself takes 8 minutes to complete. The train being loaded should depart before the arriving train is no closer than one minute away. Each car of a train accommodates four units. Loading a car is estimated to take 8 seconds per unit. Unloading is estimated to take 6 seconds per unit. Suppose that (unlike actual roller coasters), only one car can be loaded or unloaded at a time. Unloading can NOT occur at the same time as loading. To maximize the number of potential units, how many cars should the train be made up of?