Sunday was spent racing in Assen. My Mango is no longer close to being a competitive racing velomobile. Other newer designs are much quicker.
My average speed was about 40 km/h, which requires pedaling with a continuous output of about 220 W for the 47 minutes or so of the race. The Mango goes significantly faster with the same effort as is the case for my my racing bike or my two wheeled recumbent, but I still finished last! That's OK. I do this for fun, not with any expectation of winning.
The fastest designs have racing hoods, enclosed wheel arches, a lower seating position (smaller cross section as seen from the front) and a more aerodynamic form. They're also lighter. These things definitely let you ride faster with the same effort, though for everyday use the differences are not so great as on the track.
I had a racing hood for a short period. These things make a surprising difference - I could go 10% faster with just that addition and the same Mango, but I found that I overheated quickly on the track and that it was absolutely lethal to use on the road so I got rid of it.