The aerodynamic advantage of velomobiles usualy comes around 35 km/h. But velomobiles are not really a light vehicles, at least the cheaper one (around 5500 EUR), and one might have a problem to reach such speed reguraly. Than they might be interested in adding an electric engine into them which would help to overcome this problem.
In last couple of days, a link to this article appeared on many blogs. As we think it is quite interesting to read it, we also put a link here. But be prepared, it is really a long reading.