Subaru may now have ties to Toyota, but when it came to its first hybrid—introduced at the 2013 New York International Auto Show—it showed its usual independent streak. The gasoline-electric hybrid system, built into the XV Crosstrek, is definitely a bit different; although taking a cue from Toyota, it uses a nickel-metal-hydride battery pack (NiMH) rather than lithium-ion. The vehicle will go on sale in November.
The configuration is unique and the system capacity is modest, but it does provide a full range of hybrid operating functions, including some electric vehicle (EV) operation, idle stop-start, acceleration assist, and regenerative braking. The conventional XV Crosstrek is U.S. EPA-rated at 25/33/28 city/highway/combined mpg. The hybrid would improve the combined number by about 11%, Subaru said, delivering 28/34/31 mpg.
Motor built into CVT
The key operating components of the hybrid system are a 10-kW electric motor built into the back of a modified version of Subaru's Lineartronic continuously variable transmission (CVT), a belt alternator-starter (BAS) assembly on the right front of the 2.0-L four-cylinder Boxer engine, and active grille shutters.
The 0.6-kWh, 100-V NiMH pack is in a reworked rear cargo area, using space formerly occupied by the spare tire, which is replaced by a small inflator kit. Loss of cargo area capacity is minimal. With rear seatbacks up, the drop is from 22.3 to 21.5 ft³ (630 to 610 L); with the rear seatbacks folded down, the drop is from 51.9 to 50.2 ft³ (1470 to 1420 L).
Total mass of the system is just 209 lb (95 kg), including the Sanyo-supplied battery pack—itself 25 kg (55 lb)—and all other specific parts, and the chassis changes to support the additional componentry.
The motor is in the back of the CVT, and ahead of the power transfer clutch of the AWD system, so engaging the clutch with the engine off permits the motor to move the car in a brief EV mode. It can go up to about 1 mi (1.6 km) at a speed of up to about 25 mph (40 km/h), a Subaru engineer said, although road grade and throttle application (which would have to be very light) set the precise EV limits in any individual situation. Once the XV Crosstrek is rolling, in a normal driving situation the BAS will restart the engine. This mode and hardware also support the idle stop-start system. Much of the hybrid function is for acceleration assist and regenerative braking.
The 2.0-L Boxer is the same as in the non-hybrid and is rated at 148 hp (110 kW). The base transmission is a five-speed manual that will not be available in a hybrid version.
Cost decision on A/C
Unlike many hybrids, the XV Crosstrek will not include any provision for idle-stop air-conditioning such as with an electric compressor. It was a cost decision from standpoints of both the compressor itself and the size of the battery pack, which would have to be considerably larger, a Subaru engineer said.
An underhood look shows a conventional belt drive for the compressor. The blower motor will continue to operate with the engine in an idle-stop. However, during an idle-stop in high ambient temperatures—30-35°C (86-95°F)—either the engine will restart or remain running to provide A/C cooling, based on an algorithm. In normal operation, the HVAC electronics calculate cooling load, using humidity and temperature sensing, to operate the A/C while reducing engine power draw.
Several XV Crosstrek changes were developed for the hybrid, including a new gauge cluster and keyless start. Some chassis structural modifications were made to support the battery pack and other components, and more sound insulation was installed. Because of the changes in vehicle mass—300 lb (136 kg) heavier—and its distribution, ride and handling was retuned to compensate. Ground clearance for the XV Crosstrek hybrid is the same 8.7 in (220 mm) and the all-terrain functionality is maintained, Subaru said.
The exterior changes are just enough to differentiate the hybrid, including "Hybrid" badges on the front doors and tailgate and new aero-type aluminum wheels. A specific green exterior color is offered.