I've not used the BT audio much as I tend to use the USB, but since having my new phone I've been using it more.

However the sound keeps distorting. It sort of crackles every so often.

I thought it might be my phone but I have since tested my phone with two other bluetooth audio devices and it works perfectly with them and I have tested another phone with the Mondeo and it has the same problem.

I would say it is when the music is fuller so I'm wondering if the bitrate is too high?

All the tracks are 320kbps MP3. The same tracks placed on the USB stick work perfectly.

Has anyone else had similar?

The car is a 59 plate. I retro fitted the BT module to give USB and BT Audio.

I am not 100% sure if this is an issue with modern cars, if I had to have a guess sounds like interference, a friend had similar problem with home audio bluetooth multi room. Turned out his WiFi and door bell (wireless) interfering with signal. Have you got radar scanners or wireless camera's in car, are all audio leads to bt module secured and no movement at the connections. As said putting head above trench and an out of box suggestion if this helps.

I am also going bt upgrade route so would be great to hear if you get things sorted.

No, nothing wireless. Most of my journey to work is along country roads with not much in the way of life along it.

It does it all the time though.

I have tried switching wifi off on the phone as well to no avail.

My thinking is that there is a limit to the amount of data as it is always when the music is fuller. You'll just lead up to a big bit in the the music and it will always be at that point if you see what I mean.