Basically, it is a Z without satnav, so no monitor, no board computer additional functions, no phone book on the screen, no decent iPod integration with an Intravee, no radio station information on the screen and so on. Also, generally a bit light on extras .
An additional saying of "flimpering about" therefore means driving around with no idea of where you are going as there is no satnav in the car. The most classic case with flimper (Mark) driving the opposite direction from the lunch stop as his drop-on-your-dash nav system could not find it during a London meet, but the BMW systems could
All in all, it is just poking a bit of fun at flimper and he takes it well despite the fact that I depreciated his car by at least 50% or so