How to make a people's car from scratch - part two

The P42’s monocoque is made mostly of aluminium and carbonfibre for weight control, but the exact proportion of each is still under discussion. Walsh believes recycling will become a very big deal by the time we reach the hard design phase, and large quantities of carbonfibre will be costly, slow to produce and border on the undesirable from the recycling point of view. Were we doing this for real, we’d be hoping one of a range of more sustainable, biodegradable fibres currently under development might emerge over the next decade.

The electric drive motor is carried transversely in the nose, its power provided by a sled-like battery in a well-protected position under the flat floor. Front suspension is by short double wishbones to save space and the proposed rear set-up is independent by compact trailing arms, to provide a high standard of ride comfort while allowing a wide and low tailgate to take advantage of the flat floor.

One early decision has driven many others: Envisage’s confidence that designers of volume cars in 2025 will be able to depend on active, affordable, self-deploying front and side crash protection to meet forthcoming regulations. The P42 assumes both systems, and together they dramatically reduce the car’s overall length and control its width while protecting both occupants and battery in a severe side impact. The upshot is that they have allowed our design team to configure a front-drive electric car at a Golf-like length of 4.3m, while providing flexible cabin accommodation for five or even seven people.

The other major space-saving ruse is the P42’s complete absence of a classic, looming dashboard to contain its HVAC system (heater and air-con to us laymen), instruments and airbags, among other gadgetry. The HVAC fits into space liberated by the comparatively small size of the drive motor – versus a petrol or diesel engine – and by the radical proposal (for now) that much of the P42’s electrical control software will be carried outside the car, in the cloud.

This idea is already under serious discussion and Envisage believes it could become reality over the next decade. The P42’s passenger airbags should be able to be carried in the car’s pillars or its small forward cabin bulkhead and the instrument pack is proposed as an augmented reality head-up display, which can highlight external hazards. Gesture and voice control will govern other functions such as audio and ventilation.

How will the driver control the car? Our view is that autonomy will be common in easy conditions such as motorways or crawling traffic but won’t be universal, so the P42 needs a steering wheel. The steering will be ‘by wire’ rather than unbroken mechanical connection, and the same will go for braking, which will aim seamlessly to integrate retardation from friction and regeneration.

On that note, we’re proposing a single stop/go foot control. Contemporary electric cars with strong regenerative braking already approach one-pedal operation, via the accelerator, and Walsh says such systems are under serious consideration. There will be no gears to shift, and the direction of motion – forward, backward, neutral – might even be gesture or voice controlled. Work proceeds in all of these areas and more; our concluding episode will put values on motor power, battery size, vehicle weight, charging time, acceleration and cruising range.

DESIGN PROGRESS

Our Autocar-Envisage Share P42 project illustrates graphically how closely engineering and styling need to work together nowadays to create a car. How could all the rule-breaking refinements above be incorporated into a contemporary design – against a punishing schedule – without the designers knowing intimately of new stuff under the skin? And what would be the point of engineering such enticing refinements if the styling didn’t speak eloquently about it?

With the help of the rest of our designers, who have now coalesced into one team, as happens with real-world projects, Michael Mills’ original design has progressed many a mile. While keeping to the original concept, the P42’s nose now takes full advantage of the compactness allowed by deployable safety systems, the air scoops and ducts are placed where they’ll be needed, the side windows have more character, the doors are the correct shape and size and there’s a much more convincing design for the tailgate.

One more amazing refinement: Envisage’s experts are proposing a single, hugely powerful light source in the car, with a system of projectors and reflectors that use it at varying intensity for headlights, interior lights and everything in between. So ends the era (possibly) of the heavy, pricey, space-wasting traditional headlight…