I seem to have this problem as well. I complained to the dealership I bought it from. They didn't acknowledge the sound even during a long thorough test drive. Took it to another dealership and they were like "yeah bud that's not normal" and took my car in for a thorough inspection. Weren't able to narrow the sound in the 3 hours I waited. Was told to bring it back. Haven't had a chance to go back to them. Anytime you switch from drive to reverse or even put it in neutral, it makes this loud hissing squeak sound. It also seems to be less noticeable with the A/C off. If you figure out what it is, please let me know as I'm due for my 10,000 mile service soon as well.