Picture from the german wiki article
Being fast on a bicycle has a lot to do with aerodynamics so you go build an aero chassis around a recumbent and bam, fast as fuck boy.
If you do 200 Watts on a regular bicycle on a windless flat and a regular road, you're looking at going about 30kph. With this? 50kph. Obviously generalizing a lot here but you get the point.
They suck ass on hills though, because they weigh ~30kg with the chassis. not so much a problem in motion on the flat, kind of sucks uphill where aero doesn't matter. From my experience you don't see a lot of e-bike variants so far because with EU regulations the motor'd cut out at the speed you'd go for a leisurely ride on a normal bicycle, but maybe it'd be interesting to make them more hillclimbing capable.
Fun fact: in 1968 some dude did 100kph in this with by himself with no outside help.
Chassis are usually some sort carbon fibre or fiberglass and built monocoque, which means you better not ding them babies because repairs are gonna be expensive as fuck.
Prices run around 10k€ and then up to whatever you feel like paying for a new one. But they do look like old timey racecars which is fun. From personal experience of having chatted up a few of the local velomobile riders I feel like there's about a 50:50 split between buying one and somebody going fully "dad in the shed" and just building the entire thing from scratch
I really hope velomobiles and microcampers take off. They only make up maybe >1% of the traffic on my local bike trails but they're never an impediment. If I'm walking my dog, a self-sufficient camper can quietly navigate around me without scaring him. If I'm on my bike, they don't even take up the half-lane on a trail that's smaller than a single car lane and I can easily go around them. Something like this with cargo capacity and a dog seat would easily replace the few driving needs I have left in going between cities. My city would be so much more pleasant if these replaced most cars and RVs.
edit: And the best part. This e-carriage is technically in the same vehicle category so we could do CyberVictorian 1877- https://www.aliexpress.us/item/3256807756353399.html