I have a 2003 neon sxt with an automatic transmisson, it makes a growling/buzzing noise at 45 mph sometimes higher, 70 and above it is quiet, same at lower speeds. If shifted into neutral the buzzing stays until the neon drops out of that zone. No acceleration,braking handeling, ect problems. Changed CVs, but no help. It is rather loud as even I can hear it

Thanks,
Joe

 

It might be the motor mounts, transmission mounts, or struts. Or a combination of them going bad causing vibration... Look at the upper passenger strut and check to see if the rubber is broken. This may be an indicator of motor mounts going bad.