I think the Twike's top speed is indpendent of human input, and can be raised to over 100km/h by pumping more current through the electric motor. The pedaling just turns a generator that charges the batteries, which isn't very efficient, but given the layout, direct drive was too much of a hassle iirc. Assuming a powerful electric WAW (or something similar) weighs ~200kg with rider, has a Cr=.008, and going off of
this, a CdA of ~.12. Then it should need ~1.5kwh@80km/h, which could be supplied by an electric or liquid fuel motor depending on commute distance and cost. If the price of a rolling WAW'ish shell was under $1000 with cycling components... that'd be sweet.