Tobers wrote:

Inexperienced person here, but possibly helpful…

On my test drives of a D250 HSE, there was repeated annoying bonging as you describe.

It was caused by the driver assistance setting being on max, so it bongs at every speed limit change, every time you exceed the speed limit, and so on.

To turn it off, I found the driver assistance button on the centre console and pressed it to cycle from max to medium to minimum.

Annoyingly it resets to max every time you start the car but it looks to be tweakable by some 3rd party specialists to remember the last setting.

Thank you so much for all the feedback / responses....this has 'resolved' it, but as you say, I need to press the button on the steering wheel a couple of times, every time I start the engine

I seem to have opened a can of worms here