I have a MY19 X5 50i M Sport. It's got 5000 miles on it and over the last couple weeks I've noticed a squeak / whistle noise on the inside of the car when applying the brakes.
At first glance I thought it was just a squeaky brake pedal but then I found out that it also happens whenever the brakes are applied by adaptive cruise control / assisted driving.
Both the dealership foreman and I are stumped, he's actually been awesome and interested in fixing it / not just trying to write me off.
It's a very quiet whistle / squeak only on downward brake / applied brake action, and it happens even if you barely touch the brake pedal. Part of me thinks it's something coming from BDC or FEM when the brake lights are activated but I can't confirm.
