The road train is a new way to make a fuel economy up to 25%. As specialists say, the drag is the main reason of fuel consumption while riding on the long distances. Drag is the frontal resistance to the wind of a cargo vehicle. The problem is minimized if vehicles will drive one by one, very tightly. It has not been previously reachable with the trucks under the manned steering because a man-driver cannot precisely cope with the truck to synchronize it with the other tracks in the car train.
With Volvo trucks that are able to communicate wirelessly and are self-driving, the problem of synchronization is no longer an obstacle. Three trucks by Volvo have passed their way through Europe to Rotterdam going just in one second after one another perfectly coordinating their velocity and braking through a wireless connection. It allowed reducing their fuel consumption thanks to lowered drag at 25%.