I have 4000 miles on my XLR and not pleased with a whiring or whinning sound from 5mph to 40mph which has been present from day one. Dealer put in new differential but this did not stop the noise which is constant as long as I keep pressure on the accelerator to maintain a steady speed. Noise stops when I lift foot from accelerator and is not present if I incease speed or put car in neutral. Has anyone out there heard of this problem before or have any ideas on correcting? I hoped for a throaty exhaust sound like my Corvettes had.Also have owned 25 Cadillacs and have never heard a noise like this. As much as I like the car I am inclined to get rid of it if I can't find a solution.