I know it may sound odd, but check the radio. The speed sensor goes through the radio before it gets to everything else, so it can increase the volume when you go faster to drown out road noise. It can be a problem if the radio has been changed and the new one isn't compatible
When the car is started, it constantly makes a squaling/whistling noice. It sounds as if it is coming from the alternator, but it is so cramed in, it could be anything. Has anyone got any ideas of what this could be? Ford Galaxy 2.3 litre Double Overhead Cam GLX Model