Great paper on some of the crash testing data of motorcycles,scooters etc and the BMW Clever concept vehicle itself.Pretty exciting,showing us all, that without resorting to expensive materials and manufacturing procedures[Clever used standard aluminum ret,tube welded],a light weight aerodynamic motorcycle or tilting vehicle can be constructed to be very crash worthy,despite being less then a meter wide.
http://www-nrd.nhtsa.dot.gov/pdf/ESV.../05-0160-W.pdf