Even though for electric vehicles manufacturers have more freedom in regard to where they can put the motor (because it is smaller and lighter than an ICE lump), Porsche apparently wants to stick with a midship design for its upcoming 718 EV replacement. So even though the sports car will be electric, Porsche want the motor to be roughly in the same place where the engine sits in the current Cayman and Boxster models.
The goal is to have as much of the vehicle’s mass concentrated as close to its center as possible, in order to preserve its handling and agility. They want to make it feel as close to the current model as possible and Autocar points out that the platform that underpins it may also be used in future Audi or Lamborghini sports cars.
Gallery: Porsche Mission R Production Renderings
With the recent Mission R concept shown at IAA 2021, Porsche apparently used a 718 Cayman platform as the base. They then electrified it and gave it the racy, futuristic body that really drew a lot of looks at its debut.
The source quotes Porsche boss Olviver Blume as saying
When we electrify a model, we won’t do a carry-over of the combustion engine [platform] because there are too many compromises. When we are looking to future sports cars, we would develop its own platform but connected with some modules coming from other cars. But the platform will be unique.
This means the future electric Porsche sports car will not use a variation of the J1 platform used to underpin the Taycan and the Audi E-Tron GT, or the new PPE platform that will debut in the electric Macan. The main reason it will need a bespoke sports car platform has to do with one of the constraints brought by this type of vehicle.
We are, of course, referring to the fact that such vehicles need to be as low as possible, in order to have minimal drag, a low center of mass and also allow for a very low seating position for the occupants. Autocar also quotes Porsche technical chief Michael Steiner, who said
With a typical two-door sports car, you see the car is really low because to reduce drag you want the silhouette as low and flat as possible. To do that you should have the driver sitting as low as possible, and if you do that there is no space for a battery below the seat of the driver.
It’s the same reason why a lot of super-sports cars today have a mid-engine design, with the engine behind the driver. With today’s battery cell technology, the batteries are the biggest and heaviest part of the car – and this could be true for the next decade or so – so we developed what we call the e-core battery design.
Packaging-wise and centre of gravity-wise, it’s more or less a copy of a mid-engine design.
What this means is Porsche won’t actually be able to place any of the battery under the occupants’ seats, so the pac will probably run in between the seats. The manufacturer could adopt a ’T’ or ‘H’ design for it to also further aid in keeping mass concentrated in the center of the vehicle.