Hi all, I was commenting to a friend of mine who works at Tesla about the acceleration whine, which I must admit doesn't bother me at all. Anyway, my friend told me that the noise comes from the gears and went on to describe trade-offs with different types of gears between noise and efficiency. The model S uses helical gears which have multiple teeth engaged at any one time. The more teeth that engage at once the quieter the gears are but the greater the loss due to friction. Having fewer teeth engaged means greater strain on the teeth since there are fewer teeth to absorb all that force. My friend said that there are complaints that there isn't enough whine from some people.