ABSTRACT As the age of crude oil gradually finishes and political arrangements all over the world force a continuous reduction of global carbon dioxide (CO 2 ) emissions, energy efficiency and energy sustainability become worldwide a major challenge for automotive industry. The ambitious European goal of a fleet average emission for all new cars of 130 g/km CO 2 by 2012 afford an overall energy efficiency increase of the entire powertrain topologies [ 15 ]. One way to come up to this challenge is surely the electrification of powertrain systems. Nowadays, hybrid electric vehicles (HEV) represent one of the most promising technologies that combine the advantages of high performance, high fuel efficiency and low emissions in combination with a long operating range. In literature exist lots of investigations concerning the requirements of different powertrain topologies along with the corresponding individual requirements of electric motor types. Nevertheless an ideal electric traction motor cannot be given. The current research topic concentrates on motor selection criteria and tries to represent the individual pros and cons of induction motors and synchronous machines with interior mounted magnets for their use within a parallel diesel hybrid powertrain topology. The electric motor types are used as wheel hub motors on the rear axle representing an electrical add-on all wheel drive concept for passenger cars. The comparison of the two motor types is given by design and operational characteristics. The article tries to give an overview on specific electric motor selection issues, additional functionalities, fuel consumption and energy saving potentials for the investigated electric motor types and powertrain topologies.INTRODUCTION The growing demand on sustainable transportation units for passenger cars is difficult but a highly up to date research area. As the age of crude oil gradually finishes and political regulations all over the world force a reduction of the global carbon dioxide emissions, almost all OEMs worldwide put in a lot of knowledge to come up to this challenging task. Future targets considering 20 years and more from now require a significant increase of the overall vehicle efficiencies. By now the strong presence of diesel engines has prevented a substantial diffusion of hybrid passenger cars in the European automobile market [ 1]. Basically, both technologies represent effective solutions to reduce the fuel consumption of passenger cars. From a middle-term point of view, diesel hybrid architectures represent interesting efficient technical solutions to come close to the CO 2 emission targets. By now, different hybrid powertrain architectures come to mass production, besides, many of them are planned to start production within the next years. Considering a long-term point of view, there will probably exist a big diversity of economical, technical and sustainable powertrain architectures. Motor Selection Criteria and Potentials of Electrified All Wheel Drive Concepts for Passenger Cars by Add-on Wheel Hub Motors on the Rear Axle2010-01-1307 Published 04/12/2010 Johann Willberger, Martin Ackerl, Andrés Rojas and Haymo Niederkofler Graz Univ. of Technology Copyright © 2010 SAE InternationalDownloaded from SAE International by University of Liverpool, Monday, August 13, 2018Fig. 1. Well-to-wheel analysis of different powertrain topologies. The left side represents the energy demand, converted into gasoline equivalent in liters per 100 km. The right side of the picture shows the CO 2 equivalent in grams per km [ 2]. The well-to-wheel analysis in fig. 1 describes how efficient the fuel cycle and the use phase of the presented vehicles are. The grey bar shows the energy demand for production and delivery of the fuel. The red bar represents the energy equivalent for the use of the fuel over a distance of 150.000 km. The data is given for an A-Segment conventional vehicle1 [2]. Focusing the electrification of pow