I've just picked up one of
these for £4.30 and downloaded the OBD Car Doctor app from elm327.com onto my Android phone.
The free app is fairly basic- rpm, coolant temperature and not much more. The full functions only become available when paying for the Pro version. (~£14)
Not sure how much info is available on the Z3 as its OBD is not fully compliant but I would expect to see trouble and servicing codes and be able to switch them off. There is also a data logger function.