Luckily the Z4's the first car I haven't had to figure out a bike carrying solution too - this was always my area of "expertise" on other car club forums LOL. I've got a VW T5 to do those duties now
I did think this was the best solution though: http://www.birdautomotive.com/Bike%20Rack%20BMW%20Z4.htm
BMW Z4 Bike Rack inserted into Receiver Pipes:
The Z4 trunk opens without touching the Rack, Two Straps from inside the Trunk attach to the Rack. Paint is protected:
Rack stores easily in the trunk:
I did think this was the best solution though: http://www.birdautomotive.com/Bike%20Rack%20BMW%20Z4.htm
BMW Z4 Bike Rack inserted into Receiver Pipes:
The Z4 trunk opens without touching the Rack, Two Straps from inside the Trunk attach to the Rack. Paint is protected:
Rack stores easily in the trunk: