IN PART BY BOGGLING MY MIND: How Electric Superchargers Work. “Essentially a turbo’s compressor mated to a DC electric motor, this supercharger can spin to 70,000 rpm in less than 0.4 second, supplying 8.7 psi of boost before the HyBoost’s larger exhaust-driven turbo wakes up. Ricardo met its goal of increasing the Focus’s fuel efficiency from 39 mpg to 59 in European test cycles.”