Thats good advice about the aerials - But I fitted a cheap chinese stereo last year in another car and using the same aerial it went from basically perfect to lousy, also due to the poor electronics used there was a slight eletric buzz picked up all the time, even with the volume at zero and the engine off so I am cautious when it comes to chinese electronics , there not all like that I am sure but picking the good stuff from the bad is tricky. But on the other hand the bring together maybe features at prices that cannot be ignored.
One thing I am struggling with regarding an android unit is its functions without internet connection. Google maps for instance, I know you can download a section of maps to work offline but its only a certain distance it can cover, when I use the sat nav I am normally on the other side of the country so it would be no use - am I supposed to link to my phone and use its data all the time or buy a 3g/4g dongle ? or am I missing something as I dont like the idea of paying to use my satnav.
cheers
Sounds like the built-in tuner was of a very poor quality.
In order for some of these modern android units to access the internet, there's a number of options:
1. Tethering to your phone by Bluetooth or direct Wi-Fi
2. Buying a 3G/4G donglee and inserting your own separate sim card
3. Tethering your phone directly using a USB cable
You can also rely Android Auto, which can used the Maps/Navigation feature from your phone but present it on the stereo screen.
On your other point, the Android 7.1 units that are purposed built for the Mazda, I would not recommend them unless they are updated with the latest CPUs, 4Gb memory and 32Gb ROMs running Android 8, as there's a massive difference in performance.
The Android 8 models (that unfortunately aren't custom designed for the Mazda 6), bt are standard double din fitments have a much slicker interface and allow you to run two apps side by side on the same screen e.g. radio and navigation, so you don't have to flick from one app to the other. The faster CPUs and greater memory add to that super fast start up and the difference in performance is like night and day. There's roughly a £100 difference, but in my opinion its worth it.
This is why I still recommend buying a fascia to insert a double din unit in. It takes about 10minutes to fit one in and attach the double din stereo.