This book deals with the simulative prediction of efficiency and CO 2 -emissions of future powertrain systems for the year 2040. For this purpose, a suitable simulation environment is first created. This is followed by a technology extrapolation of all relevant powertrain systems, for combustion engines, electric drives, fuel cells as well as all relevant additional components. These components are then used to build 57 vehicle variants for the simulation. Finally, extensive simulations of the vehicle variants are carried out, evaluated and compared. Comprehensive tables of results are available for all simulated vehicle variants. The evaluations are of interest to anyone concerned with energy consumption and CO 2 -emissions of future vehicles.