They have got to be kidding. Another SLR derivative? Before the Mercedes-McLaren supercar speeds off into the horizon, it will have spawned no less than six different versions - including the original coupe, the Roadster, 722, 722 GT, the upcoming "Speedster", and this latest variant - if the latest reports are to be believed. We would have thought that the spied Speedster version would have been the last, but then spy shots surface of what appears to be a 722 Roadster.