There should be a lot of signals to perceive where the user is sitting. If the phone is resting in the center console, the accelerometers can tell whether it is being lifted up to the right or to the left of the car whenever it is being used. It could tell whether it is resting in the center console or the left or right side of the car depending on the shape of arc, distance travelled, centrifugal forces whenever the car follows the road around a left vs. a right turn.
If they care about accuracy to put in the engineering investment, it could be right a very high percentage of the time.
If they care about accuracy to put in the engineering investment, it could be right a very high percentage of the time.