Interesting information Nathan. I've never owned a coupe, although always loved the design. The boot space of the Z4 has always been a big selling point for me and the ability to fit 2 full sets of gear + shoes / etc in the boot is something that will forever separate it from other 2 seater rivals.
I've had a push trolley (Stewart Z3) and that goes in the boot easily with the full bag (driver and woods still in), but I've never had an electric one due to the extra size, weight and hassle. Unfortunately I have no power in the garage and am just too lazy to carry batteries about, charge them up, carry them back down, plug everything in, etc.