I have noticed a low humming noise when I take my foot off the accelerator going at speed, usually above 80kmph. It is louder when taking my foot off at a higher speed. As soon as I put my foot on the accelerator pedal it stops, take my foot off it hums and will disappear when dropping below 80kmph. I know the car is full of leaks, would that be a source? It is hard to pick where the sound is coming from but at a guess somewhere in the engine bay area. The sounds is also strange, a bit like a soft high pitch humming. Any other ideas? Cheers!