When my car is idling in Drive as well as at low speeds, I hear an obnoxious rattling noise. It has gotten louder over the last few months. I only drive the car local in the summer while I am home from college, but I will be going back to school in September and I have to drive home about 80 miles every weekend to work and I don't want it to get worse. I asked my friend who is a motor head about this and he said either something is loose or it could be the catalytic converter. I hope that it is only something loose. I need to get it checked out, and I will soon, but I was just wondering if anyone who reads this has any input on how to help. Thank you.