Audio signals of 100 megahertz? They have perfected ultrasound then.
And where is the engine stored when not in use? It'll need a garage, with room to spare, equipped with a hoist.. or require a drive to a storage facility before a journey can even be started? On a more practical note there is now a diesel / electric hybrid, from mainstream car company Peugeot. It has separate drivetrains like the concept car in the article, but uses them to give the option of 2 or 4 wheel drive. http://www.reghardware.com/2012/03/06/preview_peugeot_3008_hybrid4_worlds_first_diesel_electric_hybrid_car/
Previous research has linked high noise levels, such as found on aircraft, with the perception of blandness in food. http://www.bbc.co.uk/news/science-environment-11525897
Maths fail in article. $4000 / $100 != 400x