I have a fair few miles on my 21, only issues I have had (drive wise) is a catalytic converter replacement. I love it otherwise.
Let's not get into the satnav, bt, or wifi issues..
What I have found if you have two phones in your list the quickest one to connect to the sync 4 is the only one that works. Typically my wife's as well climb in.
She has the iPhone , I have android.
My issue is more wifi related with Android auto. It will randomly drop the android auto connection typically when I'm using it and I have to turn it off and back on, not only the wifi on my phone but the Bluetooth as well. It MAY connect again, 50% chance.
It really is so frustrating and I...