Hissing sound from brakes?
 

I just got a brand new 2015 cx5 touring. It only has 300 miles on it. Everytime I drive (not only during braking), there is a hissing sound (like two metal plates rubbing against each other). I took it in and the service guy said its because its a new car, the brakes are likely rubbing against the rotor. It should go away when I drive it more. Is anyone having the same issue?? It's a brand freaking new car! Should not be making any sounds right?!

Sorry, but your description is so vague it's impossible to imagine what it might be.

Does it do it all day every day or just when you start driving in the morning?

Around 15mph, the sound starts. It's on and off during every drive. I hear it when I roll down the window. Louder when driving close to a wall or other cars. Sounds like it's coming from the front wheels. Imagine two metal plate clashing against each, that's the sound.

Can the brakes rub against the rotor as the service guy suggested?

Brake pads should not be rubbing against the rotor to the extent that your getting a noise as you described even if the vehicle is new. If it's the brakes causing the noise my guess is that you have a sticking caliper or possibly a warped rotor. A warped rotor will cause a steering vibration when braking. A stuck caliper may cause the vehicle to pull to one side when braking hard and create excessive brake dust on the rim, but if you caught it early these symptoms will not be obvious until they get worse.