I came across a BMW C1 like this one on my way home today.
Unfortunately, I couldn’t stop and take a photo so I did a quick Google search and came up with this one. I also came across this site which has loads of photos of the BMW museum in Munich. Lots of nice old bikes on show.
I never really understood the point of the C1. It was aimed at commuters, but it was cumbersome and far too expensive. Added to which, it’s small engine capacity (125cc or 175cc) made it unsuitable away from town centre traffic. I did once see one on the motorway and it was painful to watch its rider try and cope with other, faster traffic while getting blown all over the place by a swirling cross-wind.