haha marty! this one is a simple one !! >>
in an Auto car, when you select 'Drive' you feel the gearbox 'engage' and the car kinda slightly jerks forward. If you have your foot on the brakes it means the car wont go any further forward. However, if you foot on the brake pedal is only applying a 'little' pressure to the brakes then the 'creak' sound you hear is the wheels trying to turn against the reduced clamping force of the brake pads on the brake discs.
To test this, apply firm pressure and select Drive or reverse, you'll feel the gearbox engage but no creak sound and no movement of the car.
Then do the same with lighter pressure on the brakes. At some point you'll hear the creak and the drive power starts to exceed the brake pressure you are applying.
Your brake linings are not low in this instance. Although over time of course they will wear down and be less effective, but won't have an such an effect on this issue right now
Hope you understand by what I meant there!
Cheers! Dennis! West London UK!