For me it is the old arms forward and up a bit to grip the steering wheel.
At times I still get arm fatigue even if I hold lower on the steering wheel, then I change hands often.

Many have used small travel pillows or those baby support pillows - boppies??


I think it is just another one of the postures that closes the area and causes the temporary impingement /compressions while we are driving.

Plus you may be holding more tension while you are driving too especially if some brain fog is going on..
muscle tension clamps down on all fluids that need to move thru the body, blood, lymph, nutrition, cleansing of the toxins.