An all-electric concept car from Porsche is expected to make its appearance at the Frankfurt motor show this September, and is said to hint towards the Pajun sedan set to launch sometime around 2017-18. According to reports, Porsche will preview the production Pajun with a ‘connected’ concept which measures 4.8m in length — making it shorter than the 5.0m-long Panamera.
Sister publication, Autocar UK, had revealed back in May that there would be battery electric and hydrogen fuel-cell versions of the Pajun, and that the car's powertrain would be mounted in the rear. Ulrich Hackenberg, R&D boss of Porsche’s parent company, Volkswagen Group, spoke of Porsche’s plans for electric cars at a press gathering on the night before VW’s annual conference in March. At the event, Hackenberg surprised industry observers with additional plans for a hydrogen fuel-cell vehicle.
The Pajun is said to take size and appearance cues from the Panamera Sport Turismo, first revealed in 2012.
The EVs will be built on an adaptation of the upcoming MSB platform, which will be used for the new Panamera and future Bentley models. The version powered by a fuel-cell stack looks likely to arrive in limited-production runs shortly after the launch. It’s possible that the battery electric version of the car will be called the Porsche 718, and the fuel-cell version, the 818.
The clever packaging of the new car also makes it easy to produce it in both battery and hydrogen-powered forms. This will give Porsche a big cost advantage compared with existing fuel-cell vehicles such as Toyota’s Mirai, which uses a bespoke platform. According to the uncovered patents, Porsche engineers have designed a new structural rear-mounting system for the electric-drive motors. This makes the powertrain itself part of the ‘eMSB’ structure, which will help to stiffen the rear end, improve the overall rigidity and ensure resilience in a rear-end impact. In addition, company engineers have patented something called an ‘impact plate’, also part of the platform’s new structure. These plates will be fitted between the battery cells, running across from one sill structure to another. This will give the floor greater rigidity and improve side impact performance. The batteries themselves use ‘pouch cells’ and are mounted in rigid frames.
At the front, Porsche engineers have designed a new, patented “supporting frame” with “a cross member and stiffening struts running diagonally… to form a load path that runs obliquely”.
The rear-mounted electric powertrain is expected to be similar in principle to that used in the Audi R8 e-tron, with two motors, one for each rear wheel. However, the Porsche design is more advanced. The patent describes it as a “hollow portal axle… that accommodates two electric motors”. The assembly also has a step-down gear mechanism for each wheel.
Porsche will also be able to retain an independent rear suspension system and the twin rear motors will be able to deliver a significant amount of torque vectoring, greatly aiding turn-in. This rear-engined arrangement is not only relatively space efficient but also means there’s room under the bonnet for a fuel cell stack. No engineering detail has yet emerged on how Porsche will be able to package gas tanks and a small battery pack into the eMSB architecture.
The carmaker is also developing its own induction charging system to allow the pack to be topped up without the need for cables and heavy-duty sockets while parked at the owner’s home.