Having experienced these things back in the day, at least the 3-wheeler, it has to be said ......... they are fun around town, but v.slow & roll over incredibly easily. Once on their roof, you cannot get out as the clam-shell door won't open & the sliding windows cease to slide. The old chugging BMW 300 single doesn't like being inverted & the smell of leaking petrol gets a tad scary. Thankfully some kind folk helped promptly. I can confirm that they will seat 5, with the roof open, but I can't even imagine being that stupid out on the road these days.
This one looks to have the twin drive wheel set up, which improves rear grip. The KR200 always looked the more exciting drive, but they disappear under the bonnet of an SUV out on the road.
Personally, late 60s I ran a Berkeley for a while, whilst taking driving lessons & waiting to get my VW on the road. Front wheel drive 325cc, it was fun, but lift off over-steer pretty scary, especially in the wet.