The project Safe road trains for efficient transport, SERET, has carried out research on platooning with heavy vehicles. Platooning means that two or more vehicles drive with reduced distance to minimize drag and thereby minimizing fuel consumption and emissions. A reduced distance also increases the capacity of the road. Safety is enhanced as the vehicle communicates their maneuvering over radio to control longitudinal and lateral position. The project has carried out research and development in a number of areas. Use cases and safety analysis have been made, a human machine interface has been developed and evaluated as well as algorithms for longitudinal and lateral control. Focus group interviews with drivers have been conducted to collect their needs and requirements, as well as evaluations of user interfaces in a truck simulator. Extensive computer simulations have been made of drag. Detailed simulation of fuel consumption has been made for different distances, control algorithms and different types of power trains such as conventional diesel trucks and electrical hybrids. Special attention has been devoted to the radio communication between the vehicles, as Vehicle to Vehicle communication (V2V) is essential for safe and energy efficient platooning. Finally a system solution has been implemented in three vehicles and extensive validation has been made on track as well as on public road. The vehicles participated, amongst other, in the European Truck Platooning Challenge 2016 driving between Gothenburg and Rotterdam.