First thing, check
http://www.pistonheads.com/gassing/t...f=72&t=1610533 to see if you have a compatible model, build currency and options.
If you have, you need to buy Apple CarPlay via the BMW ConnectedDrive portal (
http://www.bmw.co.uk/en_GB/topics/ow...roduction.html). You'll need to have created an account and added your BMW to it. Think is was £235.
Anyone who has ordered their BMW more recent and added Apple CarPlay to their spec at order time (think it is now an option in the configurator) can obviously skip the above step.
Finally you need to go into the iDrive. If I recall correctly I saw some instructions telling you to press and hold the voice activation button for several seconds to connect your phone to the car as an Apple CarPlay device. This didn't work! What you need to do is disconnect your existing phone pairing via the iDrive, then reconnect it selecting the Apple CarPlay option rather than the usual Bluetooth option.
That should do the trick!