Volkswagen has launched its second plug-in hybrid based on a high-volume production model: the Passat GTE, available either as a sedan or Variant (wagon)—the first plug-in hybrid from Volkswagen to be sold as either. (Earlier post, earlier post.) The Passat GTE and Passat GTE Variant will arrive on the European market this autumn; in the first few countries advance sales have already begun. In Asia the launch will also be this year. In terms of the brand, the Passat GTE is a basic building block in Volkswagen’s electric motoring strategy.
Together with the plug-in hybrids from Audi (A3 e-tron, Q7 e-tron and R8 e-tron) and Porsche (Cayenne S E-Hybrid and Panamera S E- Hybrid), Volkswagen AG now has ten models in its portfolio driven wholly or partially on electric power. (The Volkswagen brand contributes the Golf and Passat GTE plug-ins, the low-volume XL1, and the battery-electric e-up! and e-Golf.) The Passat GTE is the first plug-in hybrid model being sold by the Group in the high-volume segment of large family cars.
Global annual sales of all plug-in hybrid electric vehicles (PHEVs) are forecast to quadruple within three years from 218,000 in 2015 to 893,000 in 2018. By 2022, PHEV sales are predicted to climb to almost 3.3 million. The categories forecast to sell the highest volumes are the A segment (Golf GTE) and the B segment (Passat GTE).
|Volkswagen brand major plug-in hybrids|
|Golf GTE||Passat GTE||Passat GTE Variant|
|Fuel consumption (combined), l/100 km||1.7 - 1.5||1.7 - 1.6||1.7 - 1.6|
|Electrical consumption (combined), kWh/100 km||12.4 - 11.4||12.8 - 12.2||12.9 - 12.4|
|CO2 emissions (combined), g/km||39 - 35||39 - 37||39 - 37|
Passat GTE offers combined system output of 160 kW / 218 PS / 215 hp, combined cycle NEDC fuel consumption as low as 1.6 l/100 km (147 mpg US) and combined cycle electrical consumption as low as 12.2 kWh/100 km (Variant: 12.4 kWh) with an all-electric range of up to 50 kilometers (31 miles). Under normal operating conditions the new Volkswagen always begins its journey in all-electric mode. The front-wheel drive Passat GTE accelerates to 100 km/h (62 mph) in less than 8.0 seconds and achieves a top speed of more than 220 km/h (137 mph); in E-Mode, 130 km/h (81 mph).
Volkswagen uses a turbocharged direct gasoline injection engine (1.4 TSI) and a three-phase permanent magnet synchronous electric motor to power the Passat GTE. The 1.4 TSI engine (one of the EA 211 series) in the new Passat GTE develops its maximum power of 115 kW / 156 PS at a low 5,000 rpm. The maximum torque of the four-cylinder engine is 250 N·m (184 lb-ft), which is available between 1,600 and 3,500 rpm. With its ultra-rigid crankcase made of die-cast aluminium, and various other technical refinements, the 1.4 TSI of the Passat GTE is very lightweight at 102.8 kg (227 lbs).
As it is possible to drive the Volkswagen for relatively long periods in all-electric mode, weeks may pass with the internal combustion engine never or scarcely being used. Specific technical measures have therefore been taken to configure the 1.4 TSI for this kind of use as well. A few examples: A polymer coating was applied to the main and connecting rod bearings; a coating of special hard materials was applied to the piston rings; and special modifications were made to the bearing shells and piston play.
Full integration of the exhaust manifold in the cylinder head lets the 1.4 TSI reach its optimal operating temperature very quickly after the engine is started. Another key aspect of the engine design is thermal management.
Volkswagen engineers designed a two-loop cooling system for the 1.4 TSI; a low-temperature loop flows through the intercooler and turbocharger housing; it is supplied by an electric pump with need-based control. Passenger compartment heating comes from the cylinder head circulation loop, so that it warms up quickly, like the engine.
Moreover, due to the design of the exhaust manifold, Volkswagen was also able to opt for a compact single-scroll compressor as the exhaust gas turbocharger, thus reducing the weight of the cylinder head and turbocharger unit. Numerous other internal engine modifications also improve the fuel efficiency of the TSI engine with its two overhead camshafts.
Variable timing of intake camshaft. The intake camshaft was designed for variable valve timing to reduce emissions and fuel consumption further, and to improve drive-away torque in the lower rev range. There is also an exhaust camshaft adjuster. That allows an even more spontaneous response from low revs; at the same time, torque is improved at high engine speeds.
The maximum injection pressure of the 1.4 TSI is 200 bar; advanced five-hole injection nozzles precisely deliver up to three individual injections to each of the cylinders via a stainless steel distributor bar.
DSG with integrated electric motor. The newly developed 6-speed gearbox incorporates, in a single compact assembly, the electric motor, disengagement clutch and dual clutch gearbox (DSG), that was specially developed for hybrid use.
Whenever possible, the disengagement clutch disengages the TSI from the driven front axle and shuts it off—such as in phases of “coasting”; in this case, the Passat GTE makes use of the car’s kinetic energy and coasts without any added propulsive power.
The 85 kW / 115 PS (at 2,500 rpm) electric motor develops a substantial maximum torque of 330 N·m (243 lb-ft). The high-revving motor has a maximum speed of 7,000 rpm and forms a compact module together with the 6-speed DSG. The electric motor is mounted on the input shaft between the dual-mass flywheel of the disengagement clutch (to disengage the TSI) and the components of the 6-speed DSG. Power electronics regulate the motor’s torque and speed.
In order to integrate the electric motor fully in the gearbox, engineers shifted the 1.4 TSI 57.5 mm to the left, when viewed from the front. With the exception of the mechanically activated parking lock, the DSG is controlled entirely by an electro-hydraulic control module (mechatronics). Analogous to the 6-speed and 7-speed DSG for conventional drives, in the new DSG power flow is distributed via a coaxially split driveshaft, each with an upstream driving clutch, to two gear-train halves.
The DSG executes shifts in fractions of a second without any interruption in propulsive power. The two drive clutches (K1 and K2) are configured for input torques of 400 Nm each; the maximum input torque for the disengagement clutch (K0) of the TSI is 350 N·m (258 lb-ft).
Lithium-ion battery. Positioned in front of the rear axle, the lithium-ion battery pack comprises the cell modules, the battery junction box (BJB) and the battery management controller (BMC). Each of the total of eight modules is formed by twelve cells along with the cell electronics; the cells themselves add up to a rated voltage of 353 V and rated power of 9.9 kWh total capacity (8.7 kWh usable in the pack).
When the car is not in use or in the event of a crash, the Passat GTE’s electric power is automatically cut off. The BMC performs safety, diagnostic and monitoring functions, and it also regulates the temperature in the battery junction box (interface for supplying the motor with energy). The battery itself is liquid cooled; the cooling system is also controlled by the battery management controller, which continually acquires the temperature distribution within the battery and reports cooling needs to the thermal management system. Volkswagen provides a warranty on the high-voltage battery of eight years or 160,000 km (99,419 miles).
Three separate cooling loops. The cooling system of the Passat GTE fulfills significantly more stringent requirements than those in conventionally powered vehicles. In addition to the combustion engine, gearbox and car interior, the system must also maintain the electrical components of the hybrid system within an ideal temperature window.
The components are incorporated into the cooling loops in such a way that it can be ensured, first, that they reach their individual operating temperatures quickly and, second, that certain maximum temperatures are not exceeded. In the various operating states of the Passat GTE—from all-electric propulsion in E-Mode to driving in GTE mode—the circulation loops must always provide the optimal volumetric flow of coolant. This requirement was met by a system that has three separate cooling loops.
Power electronics. The power electronics system converts the direct current (DC) of the lithium-ion battery to three-phase alternating current (AC) for the electric motor via its high-power transistors. The system has the following interfaces: the traction circuit connection to the battery; the 3-phase connection to the electric motor; the plug connector from the DC/DC converter to the 12V electrical system and a connection for the high-voltage power distributor. Essentially, the module serves as a link for the flow of high-voltage energy between the electric motor and the lithium-ion battery.
A fusion of brake system and motor brake. Volkswagen has developed an electromechanical brake servo (e-BKV) especially for its electric cars. This optimizes the Passat GTE driver’s braking force in the same way that brake servos do in conventional cars. In the case of the electromechanical brake servo, however, this is supplemented by what is known as ‘brake blending’—a process in which low levels of deceleration are accomplished solely through the electric motor’s braking torque. In this process, energy is recovered by regenerative braking and stored in the battery. Stronger deceleration, meanwhile, is achieved in the Passat GTE through joint braking torque from the electric motor and the hydraulic brake system; and here too, kinetic energy is converted into electric power by regenerative braking.
Charging up. There are two different ways to charge the Passat GTE’s battery externally. In both cases, power is supplied via the charging socket next to the VW emblem on the radiator grille. As the conventional solution, the charging cable supplied as standard with the car is plugged into a 230-volt mains socket. The battery is then charged by alternating current (AC) from the mains at a power level of 2.3 kW. From completely flat, it can be fully charged (100% battery charge level) in four hours and 15 minutes.
As an option for use in garages and carports, Volkswagen offers a wall box with a CEE socket, via which the battery is charged at a charge level of 3.6 kW. In this way it is completely charged again in just two hours and 30 minutes. Like the wall box, there are also public charging stations that ‘refuel’ electric cars at a charge level of 3.6 kW.
In the Passat GTE, the charging process can be started immediately by pressing a button on the charging socket. Time-delayed charging is also possible. The selected time is set either via the infotainment system or the Car-Net e-Remote app, which is free for the first year. The app can also be used to activate charging immediately – essentially by remote control. The interior can also be cooled or heated, at a time preselected by the user.
All components are compact and lightweight. Some examples: the electric motor weighs 34 kg (75 lbs); the DSG, 98.5 kg (217 lbs); the power electronics, 10.2 kg (22 lbs); the battery pack, 125 kg (276 lbs). Including all components, the standard specification Passat GTE comes to an EU curb weight of 1,722 kg (3,796 lbs) (1,735 kg for the Variant).
Operating modes. The Passat GTE can be driven in four different modes: “E-Mode”, “Hybrid”, “Battery Charge” and “GTE”. The driver can always see which mode is active on the multifunction display of the instrument cluster.
Start-up in E-Mode. Upon starting the car, the Passat GTE drives automatically in the E-Mode (except when the battery is not sufficiently charged or the outside temperature is very low, in which case the TSI takes over immediately). When a minimum charge level of the battery has been reached or when there is very high demand for power, the drive system automatically switches over to the Hybrid mode. In this state, E-Mode is deactivated, and the Passat GTE now behaves like a classic full hybrid vehicle that charges the battery regeneratively during deceleration and automatically uses the TSI and/or electric motor, depending on the driving situation.
The charge state of the battery is maintained at a constant level in this mode. By using the E-Mode button (to the left of the gear knob), the driver can manually switch as needed to zero-emission motoring. This button simultaneously opens a selection window on the infotainment system, where the E-Mode, Hybrid and Battery Charge modes can be directly selected.
Battery Charge via menu. In addition to the E-Mode and Hybrid mode, it is possible via the infotainment system’s menu navigation to set a further mode: Battery Charge. This charges the high-voltage battery as the car moves along in order, for example, to enable a systematic switch to emission-free driving when entering a city.
Sporty in GTE mode. By pressing the GTE button (also to the left of the gear knob), the driver can switch to GTE mode, which activates the very sporty nature of the agile Passat GTE. The driver can feel the difference: accelerator, gearbox and steering characteristics are sportier. The tuning of the TSI is also more performance oriented. In addition, in GTE mode the TSI and electric motor work together, in what is known as boosting, to make the full system power and the maximum system torque available. Inside the acoustics change as well, as in GTE mode a corresponding GTE sound is produced. Starting in November, the sound that is audible outside can also be varied. In combination with the optional DCC (adaptive chassis control) the chassis set-up is made tauter.
Trim. The Passat GTE is an independent trim line. Standard features include LED headlights (for main and dipped beam); Driver Alert System; Automatic Post-Collision Braking; the Front Assist ambient traffic monitoring system including City Emergency Braking function; a rain sensor; ParkPilot for front and rear; chrome trim on the side windows and comfort seats (in the front).
In addition, there are elements of individualization that have been conceived solely for the Passat GTE. These include at the front a specific chrome radiator grille unit with an integrated blue stripe—blue being the color of Volkswagen electric motoring.
The Passat GTE features a completely redesigned bumper with a C-shaped LED daytime running light signature. In common with the blue design elements, this C-shaped signature is an identifying feature of all Volkswagen electric and plug-in hybrid models.
From the side the 17-inch Montpellier alloy wheels identify the Passat GTE as a plug-in hybrid.
The owner of the new Passat GTE can make use of the “CAR-NET e-Remote” app for functions such as charging of the battery or climate control. In addition, information on the vehicle status, state of charge of the battery, recent driving data or last parking position can be queried. It is also possible to check whether the doors are closed and the lights turned off.
Instrumentation. The new Passat GTE will be launched with the high-resolution 6.5-inch display of the standard “Composition Media” infotainment system. Options offered include the “Discover Media” (also with a 6.5-inch display) and “Discover Pro” (with an 8.0-inch display) radio-navigation systems. Both devices feature numerous additional functions in the Passat GTE. They include a “range monitor”, an “energy flow indicator”, “zero-emission statistics”, “e-manager” and – when the optional navigation system is installed – the “360° range” feature.
Range monitor: depicts the momentary electric driving range of the Passat GTE; the additional range potential that can be achieved by turning off auxiliary consumers that might be in use is also shown.
Energy flow indicator: this indicator utilizes animated graphics to depict the energy flow when accelerating (blue arrows) as well as braking, i.e. regenerative braking (green arrows).
e-Manager: up to three departure and charging times can be programmed here, and heating or cooling of the interior can be activated via the stationary air conditioning, which comes as a standard feature.
360° range: the driving range in “E-Mode” is shown by the 360° zone on the map of the surrounding area. The highlighted zone depicts the one-way electric driving range of the car. Charging stations can be displayed and used in route calculation.
On the left side of the instrument cluster the Passat GTE’s power meter supplements the tachometer and shows information such as whether the high-voltage battery is being charged by regeneration or whether—and how much—energy is being consumed. The speedometer is still on the right side. A color display (multifunction display Premium), which is located between the power meter and speedometer, continually displays the electric driving range and the momentary operating mode. In a separate LED field in the lower segment of the multifunction display, the “READY” message also appears after starting the e-motor, indicating that the car is ready to be driven. This is done because the electric motor cannot be heard when the car is stopped.
Active Info Display. Volkswagen is offering an instrument cluster that has been designed as a full interactive display in the new Passat GTE as an option: the Active Info Display. All instruments—thus also the specific displays in the Passat GTE—are implemented virtually by software. Navigation information can be shown in 2-D or 3-D views on a 12.3-inch display. Its resolution of 1,440 x 540 pixels enables extremely precise, high-quality graphics and interactive display of all details.
As an example, in Navigation mode, the speedometer and tachometer are relocated to the sides to make more room for the map display. Information on driving, navigation and assistance functions can be integrated into the graphic areas of the speedometer and tachometer as needed. Data that is displayed on the center console via the infotainment system, such as phone contact pages or CD covers, can also be shown in the Active Info Display in the Passat.