Having already made the leap into hybrid drive-trains with the GT3 R Hybrid and 918 Spyder, Porsche has now delivered a taste of possible future all-electric models by showcasing two Boxster E prototype variants at the Michelin Challenge Bibendum in Berlin last week.
Designed to retain the driving dynamics of their ICE driven brethren, the 4WD and 2WD prototypes are being used to investigate the integration of EVs into the company's infrastructure as well as "explore the everyday practicality of all-electric vehicles."
Boxster E 4WD
The 4WD Boxter E is driven by two electric motors - one at each axle - which produce a total power output of 180 kW and a maximum total torque of 540 Nm at 12,000 rpm. This translates to acceleration of 0-100 km/h (62 mph) in 5.5 seconds, a top speed limited to 200 km/h (124 mph) and, according to Porsche, a driving experience equivalent to that offered by the Boxster S ICE production model.
The vehicle layout sees the front drive unit replace the fuel tank and the rear unit located where the manual transmission and exhaust system would be found on a conventional model. A central electric control unit synchronizes the two electric motors and controls the front and rear torque distribution while a recovery system harvests energy during braking. Use of the recovery system can also be modified using buttons in the steering wheel to deliver "a sort of on-demand engine brake."
Boxster E 2WD
Two rear-wheel drive only Boxter E prototypes were also rolled out in Berlin last week. Sans one motor, this variant produces half the toprque and power of the 4WD prototype (90 kW and 270 Nm) and has performance figures of 0 to 100 km/h (62 mph) in 9.8 seconds with a top speed of 150 km/h (93 mph).
Range, recharging and the sounds of silence
Both Boxster E variants draw power from a 29 kWh, 440 cell lithium-iron-phosphate with a nominal voltage of 3.3 V and capacity of 20 Ah per cell. Located where you would find the engine in a Boxter S, the water-cooled battery accounts for 341 kg of the car's 1,600 kg overall weight and delivers a a range of around 170 kilometers (107 miles). The "fuel" left in the tank is monitored via an "intelligent range management system" displayed on the instrument cluster's right-hand TFT display which shows remaining range and tells the driver how many extra miles they will gain by turning off the air conditioning system.
The charging port is located at the front end and a full charge takes around nine hours through a conventional socket, though Porsche says a rapid charging function will improve on this. The design also enables the battery can be swapped out very quickly, which leaves open the possibility of a system where an empty battery is exchanged for a full one.
Porsche engineers have also taken into account the potential safety issue raised by a vehicle that can hit 124 mph in relative silence - they've integrated an Active Sound Design system that gives both drivers and pedestrians acoustic feedback.
Porsche is trialling the Boxster E EVs as part of "Model Region Electro-Mobility Stuttgart" and given the short time that it took for the Hybrid 918 Spyder to make the leap from concept to production, we may not have too long to wait before an all-electric Porsche based on these prototypes hits the road.