BMW reveals 3 Series Plug-in hybrid prototype with 117.5 mpg; next-gen Power eDrive: 2x current capacity, electric AWD

27 November 2014

BMW 3 Series Plug-in hybrid prototype. Click to enlarge.

BMW has unveiled a 3 Series plug-in hybrid prototype. Combining a four-cylinder TwinPower Turbo gasoline engine from the new Efficient Dynamics engine family with an electric motor, the BMW 3 Series plug-in hybrid prototype offers performance on a par with a conventionally powered BMW 3 Series six-cylinder model, combined with a significant reduction in fuel consumption.

In addition, BMW outlined its work on Power eDrive next-generation electrification platforms—an effort to deliver “highly electrified” plug-in hybrids with higher-powered electric motors and batteries with twice the capacity of present versions. Future plug-in hybrid concepts, said BMW, will use the electric motor—the main source of power for everyday driving—to drive the rear wheels, while a second electric motor driving the front wheels will create an all-electric road-coupled all-wheel-drive system. At the same time, an internal combustion engine will also supply power to the front axle.

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3 Series PHEV concept. The plug-in hybrid drive system has a combined output of approximately 245 hp (183 kW) and maximum combined torque of approximately 400 N·m (295 lb-ft). Average fuel consumption and CO₂ emissions are approximately
2 liters/100 km (117.5 mpg US) and 50 g/km respectively. In all-electric mode, the prototype is capable of a top speed of 120 km/h (74.5 mph), and has a driving range of approximately 35 kilometers (22 miles).

Drivetrain of the 3 Series plug-in hybrid concept. Click to enlarge.

The engine used in the BMW 3 Series plug-in hybrid prototype is based on a TwinPower Turbo four-cylinder gasoline engine that has already twice been voted “International Engine of the Year”. The electric motor and power
electronics are directly based on the BMW eDrive technology of the BMW i3 and BMW i8 models.

The motor is powered by a lithium-ion battery which, together with the battery management system and high-efficiency direct cooling system, are likewise rooted in the experience and know-how amassed during development of the BMW i models. The battery can be recharged at any household power socket and is mounted in a particularly crash-safe position underneath the load compartment.

The power electronics form a single integrated system that drives the electric motor, via a liquid-cooled inverter; manages the energy flow from the high-voltage battery to the onboard electrical systems; and provides centralized control of hybrid-specific functions. The drive torque from engine and electric motor is supplied to the rear wheels of the BMW 3 Series plug-in hybrid prototype via an 8-speed Steptronic transmission which—as on conventionally powered BMW models—makes its own additional contribution to the efficiency of the overall drive system.

Cutaway showing the electric motor and the 8-Speed Steptronic. Click to enlarge.

There is only a minimal reduction in trunk space in the BMW 3 Series plug-in hybrid prototype compared with a conventionally powered BMW 3 Series Sedan, while the interior configuration possibilities—e.g. with the folding rear seatback—are unchanged.

Cutaway of battery pack showing modules. Click to enlarge.

Like the current production models, the BMW 3 Series plug-in hybrid prototype is fitted with a Driving Experience Control switch, which is mounted on the center console. This can be used to select different vehicle settings to suit varying requirements and situations. Three different modes are available: COMFORT, SPORT and ECO PRO mode. Each features different suspension settings, different shift characteristics for the 8-speed Steptronic transmission, and a different hybrid operating strategy.

• In COMFORT mode, the electric motor’s control strategy is geared to relaxed, fuel-efficient driving. In tandem, the electric motor and internal combustion engine can also deliver high levels of power and performance when required.

• SPORT mode is aimed at maximised performance, harnessing the full combined output of the engine and the electric motor. In this mode, engine and motor are both on stream at all times, ensuring instantaneous response to all accelerator commands.

• In ECO PRO mode, the accent is on harnessing the full efficiency potential of electrification. Intelligent hybrid functionality allows the electric motor and internal combustion engine to work in tandem to maximize overall system efficiency. Efficient energy management is enhanced by variable control of the electric comfort functions such as air conditioning, seat heating and exterior mirror heating, which always operate at the most appropriate power level. This likewise helps to maximize the vehicle’s range.

At the press of a button, the driver can choose between different plug-in hybrid modes. The MAX eDrive mode provides all-electric, zero-local-emission propulsion. Selecting the SAVE Battery mode keeps the battery at a constant state of charge. If the battery is less than 50% charged, the charge level is increased. In this way drivers can ensure they have enough power in reserve to operate in all-electric mode on a later, urban section of the journey.

The BMW 3 Series plug-in hybrid prototype also features a special hybrid-adapted Proactive Driving Assistant. Integrated in the navigation system, this system manages the powertrain not only with reference to current battery capacity but also to upcoming route profile, speed restrictions and traffic conditions.

This function marks the most extensive and advanced integration to date of BMW EfficientDynamics and BMW ConnectedDrive. Whenever the navigation system is in operation, the hybrid Proactive Driving Assistant collates all the available information about the upcoming route and relays this to the powertrain controller. This information comprises both static data from the interactive map, for example about speed restrictions and gradients, and also real-time information on current traffic conditions (Real Time Traffic Information—RTTI).

The proactive energy management system then breaks the route down into its component parts, including low-speed sections, last-lap sections and gradients, before computing a proactive, route-specific strategy for managing the electric drive power right through to the specified destination.

Power eDrive demonstrator. Click to enlarge.

Power eDrive: new generation of “highly electrified” concepts. In addition to revealing the 3 Series PHEV concept, BMW said that the ongoing development and refinement of hybrid drive systems under the Efficient Dynamics program is geared in particular to maximizing the amount of time the vehicle spends in electric mode. The overall efficiency of a plug-in hybrid vehicle is clearly closely related to its all-electric driving range.

To ensure that this shift to increased electric operation goes pari passu with typical BMW dynamic performance, everyday practicality and maximum long-distance capability, the BMW Group said it is developing a new generation of “highly electrified” hybrid concept models.

Highlights of the future models’ Power eDrive technology will include significantly higher-powered electric motors and batteries with twice the capacity of present versions. With this technology, the BMW Group is embarking on the next stage in powertrain electrification.

The development of high-performance Power eDrive electric drive technology is aimed at increasing both the overall efficiency and the dynamism of future hybrid vehicles. Increasing focus will be placed on all-electric operation. Power eDrive technology for plug-in hybrid application will be a natural choice for use in upmarket vehicle segments too, where it will offer unrestricted everyday practicality plus good long-distance capability.

In these plug-in hybrid vehicles of the future, the Power eDrive electric drive system will contribute approximately two-thirds of the vehicle’s combined output, with the TwinPower Turbo internal combustion engine accounting for the remaining third. The drive components used in these future hybrid systems will offer combined outputs in excess of 500 kW, while the capacity of the lithium-ion batteries—up to 20 kilowatt hours—will likewise be greatly in excess of current hybrid systems.

At the same time, the performance of these future hybrid models will be on a par with that of a conventionally powered sports car.

On future plug-in hybrid concepts, the electric motor, which will be the main source of power for everyday driving, will continue to drive the rear wheels, while the addition of a second electric motor driving the front wheels will create an all-electric road-coupled all-wheel-drive system. At the same time, an internal combustion engine will also supply power to the front axle.

With its development work in the field of eDrive technology, the BMW Group is positioning itself to field the broadest possible range of high-overall-efficiency vehicle concepts. While the BMW i3 is an optimized solution for urban and suburban mobility, future plug-in hybrid drive systems will allow fuel consumption and emissions to be steadily reduced in long-distance operation as well. In other words, BMW is striving to deliver a typical BMW driving experience across a whole range of scenarios, including zero-local-emission everyday driving, long-distance trips and sporty, dynamic driving situations.