► Electric rival to Merc CLS, Tesla

► Four-door body, battery power

► 300-mile range, four-wheel drive

Porsche is busy preparing a battery-powered rival to the successful all-electric Tesla Model S - and CAR has details of this project, provisionally badged the Porsche 717.

It’s being developed on the Volkswagen group’s latest MSB architecture under development for the Panamera Mk2 and the next Bentley Continental.

If all goes according to plan, we can expect a sporty four-door, four-seater with clear 911 overtones, wrapped in a more compact footprint than a Panamera’s. Our artist’s impression above shows the kind of direction being explored by Porsche’s design department, according to our sources. Sounds like the 911 cookie cutter hasn’t run out yet…

Porsche 717: a Tesla fighter from Stuttgart

The sports car brand already offers two plug-in hybrid electric vehicles (PHEVs): one based on the facelifted Cayenne SUV and the other one on the Panamera. On an even loftier level, there is of course the now-sold-out limited-edition 918 hypercar. The logical next step therefore is a Porsche battery-electric vehicle, or BEV.

Now that the company is part of VW, it is no longer able to go and develop such new projects solo, so the power of the group is being flexed to make the Porsche 717 leap from feasibility study to factory floor.

Ground hugging and emphatically dynamic in appearance, the car that is rumoured to be badged 717 is definitely not an SUV or a crossover, CAR hears.

The battery tech underpinning the electric Porsche

While the flat-bottom Tesla features a long and wide monolithic battery pack which double-up as floorpan and structural reinforcement, the lower H-point and the sports car stance postulated by Porsche would call for a so-called topologic battery installation.

Instead of a single, square-mattress-shaped energy cell which is relatively easy to cool and to connect, the battery arrangement proposed for the 717 looks more like a mountain range with the centre tunnel acting as peak ridge, with a pair of tall bulkhead walls and smaller agglomerations in the sills, the footwell and the overhangs.

In total, a reported 108 battery pouches need to be accommodated by the body-in-white. All 717 models will feature 4wd, four-wheel torque vectoring and four-wheel steering. As a rule, there is one electric motor per axle which will either be steel-sprung or feature an electrically-controlled air suspension system.

When is the Porsche 717 going to be on sale?

It is hard to judge whether Porsche’s provisional launch date of early 2019 is realistic or wishful thinking. The same applies to the engineering concept which, according to one insider, is set to provide three different e-power stages rated at 400, 500 and 600bhp, reflecting the choice of power outputs available in the Model S. The average driving range target is in excess of 300 miles.

Together with the US specialist supplier Quantumspace, Porsche and sister brands VW and Audi are developing a new induction charge process designed to match the Tesla principle in duration and to beat it in convenience.