Z3 is my 3rd roadster-bodied sports car and I've also owned numerous motorcycles including several in the "roadster" category. Among bikes, that generally means a classic-styled "open" bike (no fairing, windscreen maybe) that is suitable for both comfortable cruising and moderate sport riding (i.e. does not have the extreme riding position of a full-tilt sports bike).
I currently own a '98 Triumph Thunderbird 900 which is the quintessential "roadster." Who else owns a bike and what?