How long does that groaning noise last?
Is it at all possible that the noise is coming from the back of the car?
I ask these questions because the e-brake/parking brake can emit a very brief groaning noise if it is not applied firmly. In a situation like that, the car will roll very slightly until the “Park Pawl” in the transmission stops the car from moving, but until the Park Pawl stops the car, a loosely-applied e-brake can emit a groaning noise.