Kenyon1976

Had my car for almost 3 months, there was a slight rattle in the front passenger door, it's now very pronounced, if the road isn't dead smooth I hear a constant rattle.

Should I take this back to the dealership I purchased it from or the one I signed up with (much closer, other one is about 40 miles away)? Is this something they normally take care of under warranty?

I've had several new cars (Ford, Toyota, etc.), none of them had a rattle even after 100K miles.

chassis

Yes, this is a warranty repair. Take it to the dealer. Call first to make a service appointment.