2002 Oldsmobile Other

I have a 2002 Olds Alero with 80,000 miles and a V6-engine. About a month and a half ago, I had the transmission flushed, changed the fuel filter, and got new break pads and rotors. A couple weeks after I had these repairs done, I started to hear a humming noise while driving. It starts out low when I hit 15-20 miles per hour and increases in both pitch and volume the faster I drive. Also, I've noticed a dramatic decrease in my miles per gallon. Before the repairs, I was getting about 28 mpg (mostly highway driving). Now I am getting only about 20 mpg at most. I took my car in to ask about the noise and the decrease in mpg and they said I probably needed a couple new tires, so I purchsed two Yokohama tires. The noise has not stopped and I am still getting low mpg. Also, I change my oil regularly and I have not been advised to perform any other maintenance. Does anyone have any suggestions?
February 6, 2007.

After you drive it, go to each wheel and feel for significant heat differences among them, sounds like a brake may be dragging, regarding the fuel miliage.

The hum may be a wheel bearing going bad, does it change if you steer to the left or to the right?

If those spark plugs are original, I get those changed. But not untl the first two problems are resolved.

Thanks for the response. I noticed a difference in the humming noise when I steer. When I turn slightly to the right (ie - changing lanes on the highway), the noise is louder and there is a slight vibration. Also, the car makes a faint high pitch noise when I turn left at higher speeds (ie - an on/off ramp on the highway).

These problems only started after I took my car into the shop to get brakes. Could it be that they messed something up?

Feb 9, 2007.
Not in my opinion...That is any correlation between the bearing and the brakes. Thank the wonderful GM engineers on tha one.

We have replaced many alero bearing assys.--get a tiken brand!