INTRODUCTION The V olt is an electric vehicle with extended range, which can operate with full vehicle performance on battery power alone, without using its engine, so long as the battery pack has sufficient energy and power available. For most owners, the V olt is supplied with electrical energy from the grid through nightly charging, and the engine runs only when a daily drive exceeds EV range or during very cold weather. The second-generation V olt propulsion system, like the first-generation V olt propulsion system, is a fully-capable and efficient EV propulsion system that can integrate engine power to continue driving if EV range is exceeded. Whether the vehicle is operating in electric or range-extended mode, it is designed to provide full capability without compromising speed, hill climbing ability, or performance, and a similarly pleasing driving experience in terms of NVH and smoothness. The second-generation system was designed from a “blank tablet”, with the benefit of experience gained from the V olt and its customers.The mission of the V olt vehicle is to provide an electric vehicle experience allowing the typical driver to do a majority of their driving electrically, while providing the flexibility of a range-extending engine to allow for longer trips between charges when needed. The distribution of vehicle trips for a typical customer varies in both driving intensity and distance. In a grid connectable vehicle such as the V olt, the probability that a trip will be completed without requiring engine use depends on three factors: the length of the trip, the driving intensity of the trip, and the frequency of recharging [1,3]. In field usage, frequency of charging has exceeded 1 charge/day for many customers [ 4]. In terms of vehicle design, EV operation can be maximized by increasing the EV capability as well as the energy available for charge depletion. GM benchmarking of available plug in hybrid vehicles show that the V olt has significantly more all electric range, and a higher level of EV capability than the competitive vehicles studied ( Figure 1). For the typical customer, these metrics translate into a vehicle that operates as an EV without starting the The Next Generation “Voltec” Extended Range EV Propulsion System Brendan M. Conlon, Trevor Blohm, Michael Harpster, Alan Holmes, Margaret Palardy, Steven Tarnowsky, and Leon Zhou General Motors ABSTRACT The Chevrolet V olt is an electric vehicle (EV) with extended-range (ER) that is capable of operation on battery power alone, and on power generated by an on-board gasoline engine after depletion of the battery charge. For 2016, GM has developed the next generation of the V olt vehicle and “V oltec” propulsion system. Building on the experience of the first generation V olt, the second generation targeted improved all-electric range, improved charge sustaining fuel economy, and improved performance. All of this was to be accomplished while maintaining the EV character of the first generation V olt which customers clearly valued. This paper describes the next generation “V oltec” system and the realized improvements in efficiency and performance. The features of the propulsion system components, including energy storage, transaxle, electric motors and power electronics, on-board charging, and engine are described and compared with the previous generation. Next, the transaxle powerflow is discussed and operation under typical driving conditions is explained. Finally, system efficiency and performance data, based on component tests, is presented and compared with the previous generation. This system includes a battery pack with greater energy density, a new transaxle with integrated power electronics and motors, and an engine with optimized displacement, direct injection, and other advanced features. As a result of these improvements, the second generation V olt vehicle is projected to achieve a 30% increase in EV range, an 11% improvement in charge s