I have a humming noise coming from the center to rear of the car on 2003 Saturn Vue

I drove my car on an 800 mile round trip, then let it sit for 3 days. When I started the car, I have a humming noise coming from the middle to rear of the car (its hard to tell)

1 answer 2 comments
If it is humming when stopped, then this may be a noisy fuel pump or an exhaust rattle. Noises are tough to figure out when you can t hear them, so try having a mechanic listen to it and see what they say.
I ONLY HEAR THE NOISE WHILE DRIVING. WHEN I COME TO A COMPLETE STOP I DON'T HERE THE NOISE ANYMORE. I just bought this about an week ago 2003 Saturn Vue Basic
I have the same problem but every time I schedule an appointment with a mechanic it stops making the noise for awhile. My mechanic says it is probably the fuel pump. I can not confirm that is the problem.