
So, as you know the e53 doesn't have A2DP bluetooth which is the stereo channel it has the older HFBT (hands free Blue tooth) which is mono and which the Iphone (and others) recognises as NOT a streaming channel.
So all you need to do is to tell your phones bluetooth to stream in mono and it will stream to the X5's HFBT unit. Turns out this isn't as simple as you may think.
There used to be a legit app in the app store which would do this but its been discontinued so for Iphone users you will have to jailbreak your iPhone. For the process is
Jailbreak>>Install activator (needed for SBSettings to work) >>install SBSettings>>instal BTMono SBSetting toggle
Once thats done flick the BTMono switch and your phone will stream audio via the cars bluetooth.
If you are on android there is a legit app called BTMono in the android store that should do the same thing (but not having a phone to test, I can't be sure).
This will also let you stream audio to a mono bluetooth headset.
Might be a bit of a faf but its free and means I don't have to spend £200 to listen to already low fi podcasts
...and there was much rejoicing