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Notes about the Jaguar XKX: 
Another characteristic feature of the Jaguar XKX are the totally disappearing side mirrors. At about 1cm thickness, the mirrors perfectly fit the shallow hatch made in the door piece when the car is stopped and they unfold again in working position when it’s turned on. This adds to both the aesthetics, and protects the side mirrors from any damages when parked.
Given a much smaller and cooler power plant than conventional, the aerodynamics was conceived in a new innovative way. The side deflector intakes of the front were made broader, so a much larger amount of air does not get stuck by the engine, instead, it flows behind the front wheels, getting out behind them and sliding along the doors and then taking another shortcut through the rear wheels and out from the big rear openings, greatly reducing the total flowing path and subsequently drag.
Almost 60% of the energy used by a typical car at highway speeds is spent to counter air friction. Obviously, that is A LOT of energy spent for a function that is indispensable, but not the primary (to push the vehicle forward). The body of the XKX is covered by a layer housing microscopic ripples of piezoelectric cells, which, stimulated by the pressure of the air flowing over them (the actual air friction experienced by the car) produce electricity that is fed back to the vehicle’s battery, increasing both efficiency and performance.
1. "Jaguar XKX." Behance.net. Retrieved on May 2nd, 2012. Images © Skyrill and Marin Myftiu Link via Behance Network