I have a new 2015 Electric Drive. It was quite noisy from wind at highway speed. I fixed it by screwing the front cover (underneath where the engine would go if it had an engine) to the front bumper with 4 stainless steel #10 sheet metal screws. Now it is wonderfully quiet.
https://photos.app.goo.gl/7KpcoHqI246mv91W2
https://photos.app.goo.gl/7KpcoHqI246mv91W2