The issue that I am having with my car is that it makes a louder rumble than usual when I am at low speeds between 1400-2000 RPM. 
Once I exceed 20 MPH, the noise goes away. The noise only occurs when I am below 20 mph at low RPMs. Any advice is appreciated. 

I took the car to my mechanic he said he did not know what the issue is. He said the noise may be coming from the transmission and it isn’t a major concern. 

Another inconvenience I am having is:

When I am at higher speeds and I press on the brake pedal I feel some play in my steering wheel. It is when I press the brakes hard, and at higher speeds. My mechanic checked out my car and said my brake pads/rotors were fine.