Extremely loud driving noise/roll-off noise Mini One F56

Hello guys! Unfortunately I have extreme problems with my new Mini One built in November 2018, 8.000km down. With a very slow ride (from about 30-40 kmh) it starts to get very loud in the interior. It sounds like roll-off noises, but in my opinion it’s way too loud. I haven’t had a louder vehicle in my life. Depending on the road surface, the volume or intensity of the noise changes. The tires are the ones that came from the factory (Michel) in Energy Saver 195/65/r16, summer tires) and still look very good. I was two times at the dealer, who told with each time that it was probably normal and Mini is always loud. Sawtooth is not available. However, it is so loud that the ears become deaf to you. I once measured by mobile phone app and there I measured at about 60 kmh inside, 70 decibels in the interior. That can’t be normal after all? Funny is that when you turn the windows down, the noise “on I have to say that the sound has been there from the beginning. I had bought it with just under 3,000km… I have already checked tire pressure. No matter if 0.2 bar more or less does not change anything. Temperature-dependent is probably not, since the noises remain the same at cold or warm outside temperatures. Do you have any idea what this could be? Or is it normal? I am grateful for every person who is interested in it. Note…